Code
P1161
BMW
P — Powertrain
Fuel Trim Adaptation Additive Bank 2 High
Views:
UK: 30
EN: 39
RU: 32
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
BUICK
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 30
EN: 31
RU: 35
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
CADILLAC
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 27
EN: 27
RU: 30
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
CHEVROLET
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 31
EN: 34
RU: 32
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
CHRYSLER
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 34
EN: 29
RU: 35
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
CITROEN
P — Powertrain
Motorised throttle position coherence
Views:
UK: 3
EN: 2
RU: 6
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
DS
P — Powertrain
Motorised throttle position coherence
Views:
UK: 3
EN: 1
RU: 4
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
GM
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 31
EN: 35
RU: 33
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
GMC
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 33
EN: 31
RU: 41
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
HUMMER
P — Powertrain
Heated Oxygen Sensor (HO2S) Heater Control Circuit Bank 2 Sensor 2
Views:
UK: 18
EN: 11
RU: 21
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
OLDSMOBILE
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 32
EN: 33
RU: 32
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
PEUGEOT
P — Powertrain
Motorised throttle position coherence
Views:
UK: 3
EN: 1
RU: 4
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
SATURN
P — Powertrain
HO2S Heater Power Stage Circuit Bank 2 Sensor 2
Views:
UK: 32
EN: 31
RU: 32
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
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Code
P1161
VOLKSWAGEN
P — Powertrain
Manifold Temperature Sensor Circuit Open/Short To B+
Views:
UK: 29
EN: 31
RU: 35
AI status
Completed
Completed
100%
Causes
- Intake air leak or vacuum leak on bank 2 (intake manifold gasket, hose, charge pipe)
- Faulty or contaminated mass airflow (MAF) sensor or intake metering fault
- Low fuel pressure or restricted fuel delivery to bank 2 (fuel pump, filter, regulator)
- Clogged, leaking or intermittent fuel injector(s) on bank 2
- Faulty or slow oxygen/wideband sensor (Bank 2) or wiring/connectors
- Exhaust leak upstream of the bank 2 O2 sensor
Symptoms
- Check Engine Light (MIL) illuminated
- Rough or uneven idle, especially at warm-up
- Hesitation, stumble or reduced power under acceleration
- Noticeable increase in fuel consumption
- Failing emissions/failed tailpipe test
- Occasional black smoke or rich odor after ECM overcompensates
What to check
- Scan for all stored/related DTCs and view freeze-frame data
- Record short-term and long-term fuel trims for both banks at idle and under load
- Observe upstream O2/wideband sensor voltages/waveforms for Bank 2
- Inspect intake hoses, vacuum lines, intake manifold gasket and charge pipes for leaks
- Perform smoke test for intake/evap/pcv leaks
- Visually inspect and test MAF sensor; clean if contaminated
Signal parameters
- Long-term fuel trim (Bank 2) significantly positive — typically > +20 to +25% indicates high additive
- Short-term fuel trim (Bank 2) showing sustained positive corrections rather than transient spikes
- Upstream O2/wideband sensor (Bank 2) not switching or showing biased readings (narrowband ~0.1–0.9V switching; wideband stable around commanded lambda)
- MAF signal should be smooth and increase with RPM/load; erratic or low readings indicate sensor/intake problem
- Fuel rail/pressure should remain within manufacturer spec under idle and load — large drops under load indicate delivery problem (check service data for exact values)
- Intake vacuum/pressure readings stable at idle and respond to throttle inputs without leak-induced anomalies
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note engine temperature, fuel trims, RPM and load at fault occurrence.
- With scanner, monitor STFT and LTFT for both banks at idle, during snap throttle and under steady load to confirm persistent high additive on Bank 2.
- Visually inspect intake plumbing, vacuum lines, intercooler/charge pipes (if turbo) and intake manifold gasket on Bank 2 side. Perform a smoke test to locate leaks.
- Inspect and clean the MAF sensor. Re-test MAF signal for correct response to throttle changes; compare to known-good pattern or data.
- Check for exhaust leaks upstream of the Bank 2 oxygen sensor — repair any leaks and retest.
- Measure fuel pressure at the fuel rail (and under load) and compare with manufacturer specs. If low or fluctuating, test fuel pump, filter and regulator.
- Inspect injectors on Bank 2: check wiring/connectors for corrosion or damage, perform balance or flow testing and replace/clean as required.
- Test Bank 2 upstream O2/wideband sensor and its wiring for correct operation and response time; replace if out of spec.
- If no mechanical/electrical faults found, check PCM calibration level and dealer technical bulletins. Perform a controlled adaptation reset if appropriate and re-evaluate fuel trims after a proper drive cycle.
- After repairs, clear codes and perform a full drive cycle to confirm LTFT and STFT return to normal and code does not reappear.
Likely causes
- Intake manifold or vacuum leak on bank 2 allowing unmetered air (most common)
- MAF sensor dirty or failing causing incorrect air mass reading
- Fuel delivery problem (low pressure or weak flow) reducing fuel available at bank 2
- Faulty bank 2 upstream O2/wideband sensor or wiring causing incorrect feedback
- Leaking/clogged injector(s) on bank 2 causing imbalance
Fault status
Status
Fuel trim adaptation (additive) for Bank 2 is higher than allowed — the PCM is adding excessive fuel to correct a perceived lean condition on Bank 2.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.5 hours
Similar codes
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