Code
P0471
Generic
P — Powertrain
Exhaust Pressure Sensor A Circuit Range/Performance
Views:
UK: 28
EN: 91
RU: 57
AI status
Completed
Completed
100%
Causes
- Faulty exhaust/back‑pressure sensor (sensor A)
- Open, short or intermittent wiring between sensor and ECM
- Corroded or loose connector terminals
- Poor sensor reference or ground (bad 5 V reference or ground)
- Excessive exhaust backpressure (clogged DPF, restriction)
- Mechanical damage to sensor or probe (contamination/soot)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Reduced engine performance or limp mode in some vehicles
- Elevated exhaust/backpressure readings or failed DPF regen
- Reduced fuel economy
- Increased emissions, rough idle or turbocharger control faults on turbo engines
- Related warning lights (DPF, turbo, or emission system)
What to check
- Read freeze‑frame and stored data with a scan tool; record live exhaust pressure PID and other related PIDs (MAP, turbo boost, DPF differential pressure)
- Check for additional stored codes (EGR, DPF, boost, MAP)
- Visual inspection of sensor, probe, wiring harness and connector for damage, contamination, soot, corrosion or loose pins
- Backprobe sensor connector: measure reference voltage (typically ~5 V) and ground continuity to chassis or ECM ground
- Measure sensor signal voltage while engine is cold, at idle and during revs; look for a smooth, proportionate change
- Wiggle wiring and connectors while observing live data for intermittent changes
Signal parameters
- Typical sensor type: analog pressure sensor (variable voltage output)
- Reference/supply voltage: ~5.0 V (measure 4.5–5.5 V depending on vehicle)
- Signal output: typically ~0.5–4.5 V linear with pressure (vehicle dependent)
- Expected behavior: smooth, proportional voltage change with engine speed/load; no sudden drops to 0 V or fixed high voltage
- Pressure range: depends on design — often reads vacuum to positive backpressure (example ranges: -20 kPa to +200 kPa); consult vehicle spec for exact values
Diagnostic algorithm
- Retrieve DTC, freeze‑frame and note operating conditions when fault set. Check for related codes (EGR, DPF, MAP, turbo codes).
- Perform visual inspection: sensor/probe condition, connector pins, wiring harness routing; repair any obvious damage.
- Using a scan tool, observe live exhaust pressure signal. Rev engine and watch for smooth change. Note values at key points (idle, 2500 rpm).
- Backprobe connector: verify 5 V reference present and stable, and good ground. If missing or unstable, trace wiring to ECM and repair.
- Measure sensor signal voltage while applying known pressure (if shop equipment available) or while varying engine load. Compare voltage vs expected curve from vehicle spec.
- Check continuity and resistance of the signal, power and ground circuits between sensor and ECM. Repair any opens/shorts. Perform wiggle test to find intermittent faults.
- If sensor wiring and continuity are good but signal is out of range, remove sensor, inspect probe for contamination and clean if serviceable, or replace sensor with OE or equivalent part.
- If backpressure seems high, inspect exhaust system and DPF for restriction; perform DPF diagnostic/cleaning or repair exhaust restrictions as required.
- After repairs or sensor replacement, clear codes and road test to confirm the fault does not return. If it persists, consider ECM input circuit testing or replacement per manufacturer procedures.
Likely causes
- Failed/exhaust pressure sensor
- Wiring short to voltage or ground, or open circuit
- Poor ground or low reference voltage at sensor
- Clogged DPF or restriction causing abnormal pressures
- Connector corrosion or bent pins at sensor or ECM
Fault status
Status
ECM has detected that the exhaust pressure sensor A circuit is producing values outside the expected range or is not performing correctly. The condition can trigger the MIL and may affect emission control functions and DPF regeneration.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
P0471
GWM
P — Powertrain
- Incorrect indicator / not adjusted exhaust gas pressure sensor
Views:
UK: 12
EN: 22
RU: 21
AI status
Completed
Completed
100%
Causes
- Faulty exhaust/back‑pressure sensor (sensor A)
- Open, short or intermittent wiring between sensor and ECM
- Corroded or loose connector terminals
- Poor sensor reference or ground (bad 5 V reference or ground)
- Excessive exhaust backpressure (clogged DPF, restriction)
- Mechanical damage to sensor or probe (contamination/soot)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Reduced engine performance or limp mode in some vehicles
- Elevated exhaust/backpressure readings or failed DPF regen
- Reduced fuel economy
- Increased emissions, rough idle or turbocharger control faults on turbo engines
- Related warning lights (DPF, turbo, or emission system)
What to check
- Read freeze‑frame and stored data with a scan tool; record live exhaust pressure PID and other related PIDs (MAP, turbo boost, DPF differential pressure)
- Check for additional stored codes (EGR, DPF, boost, MAP)
- Visual inspection of sensor, probe, wiring harness and connector for damage, contamination, soot, corrosion or loose pins
- Backprobe sensor connector: measure reference voltage (typically ~5 V) and ground continuity to chassis or ECM ground
- Measure sensor signal voltage while engine is cold, at idle and during revs; look for a smooth, proportionate change
- Wiggle wiring and connectors while observing live data for intermittent changes
Signal parameters
- Typical sensor type: analog pressure sensor (variable voltage output)
- Reference/supply voltage: ~5.0 V (measure 4.5–5.5 V depending on vehicle)
- Signal output: typically ~0.5–4.5 V linear with pressure (vehicle dependent)
- Expected behavior: smooth, proportional voltage change with engine speed/load; no sudden drops to 0 V or fixed high voltage
- Pressure range: depends on design — often reads vacuum to positive backpressure (example ranges: -20 kPa to +200 kPa); consult vehicle spec for exact values
Diagnostic algorithm
- Retrieve DTC, freeze‑frame and note operating conditions when fault set. Check for related codes (EGR, DPF, MAP, turbo codes).
- Perform visual inspection: sensor/probe condition, connector pins, wiring harness routing; repair any obvious damage.
- Using a scan tool, observe live exhaust pressure signal. Rev engine and watch for smooth change. Note values at key points (idle, 2500 rpm).
- Backprobe connector: verify 5 V reference present and stable, and good ground. If missing or unstable, trace wiring to ECM and repair.
- Measure sensor signal voltage while applying known pressure (if shop equipment available) or while varying engine load. Compare voltage vs expected curve from vehicle spec.
- Check continuity and resistance of the signal, power and ground circuits between sensor and ECM. Repair any opens/shorts. Perform wiggle test to find intermittent faults.
- If sensor wiring and continuity are good but signal is out of range, remove sensor, inspect probe for contamination and clean if serviceable, or replace sensor with OE or equivalent part.
- If backpressure seems high, inspect exhaust system and DPF for restriction; perform DPF diagnostic/cleaning or repair exhaust restrictions as required.
- After repairs or sensor replacement, clear codes and road test to confirm the fault does not return. If it persists, consider ECM input circuit testing or replacement per manufacturer procedures.
Likely causes
- Failed/exhaust pressure sensor
- Wiring short to voltage or ground, or open circuit
- Poor ground or low reference voltage at sensor
- Clogged DPF or restriction causing abnormal pressures
- Connector corrosion or bent pins at sensor or ECM
Fault status
Status
ECM has detected that the exhaust pressure sensor A circuit is producing values outside the expected range or is not performing correctly. The condition can trigger the MIL and may affect emission control functions and DPF regeneration.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
P0471
HUMMER
P — Powertrain
Exhaust Pressure Sensor Range/Performance
Views:
UK: 15
EN: 33
RU: 27
AI status
Completed
Completed
100%
Causes
- Faulty exhaust/back‑pressure sensor (sensor A)
- Open, short or intermittent wiring between sensor and ECM
- Corroded or loose connector terminals
- Poor sensor reference or ground (bad 5 V reference or ground)
- Excessive exhaust backpressure (clogged DPF, restriction)
- Mechanical damage to sensor or probe (contamination/soot)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Reduced engine performance or limp mode in some vehicles
- Elevated exhaust/backpressure readings or failed DPF regen
- Reduced fuel economy
- Increased emissions, rough idle or turbocharger control faults on turbo engines
- Related warning lights (DPF, turbo, or emission system)
What to check
- Read freeze‑frame and stored data with a scan tool; record live exhaust pressure PID and other related PIDs (MAP, turbo boost, DPF differential pressure)
- Check for additional stored codes (EGR, DPF, boost, MAP)
- Visual inspection of sensor, probe, wiring harness and connector for damage, contamination, soot, corrosion or loose pins
- Backprobe sensor connector: measure reference voltage (typically ~5 V) and ground continuity to chassis or ECM ground
- Measure sensor signal voltage while engine is cold, at idle and during revs; look for a smooth, proportionate change
- Wiggle wiring and connectors while observing live data for intermittent changes
Signal parameters
- Typical sensor type: analog pressure sensor (variable voltage output)
- Reference/supply voltage: ~5.0 V (measure 4.5–5.5 V depending on vehicle)
- Signal output: typically ~0.5–4.5 V linear with pressure (vehicle dependent)
- Expected behavior: smooth, proportional voltage change with engine speed/load; no sudden drops to 0 V or fixed high voltage
- Pressure range: depends on design — often reads vacuum to positive backpressure (example ranges: -20 kPa to +200 kPa); consult vehicle spec for exact values
Diagnostic algorithm
- Retrieve DTC, freeze‑frame and note operating conditions when fault set. Check for related codes (EGR, DPF, MAP, turbo codes).
- Perform visual inspection: sensor/probe condition, connector pins, wiring harness routing; repair any obvious damage.
- Using a scan tool, observe live exhaust pressure signal. Rev engine and watch for smooth change. Note values at key points (idle, 2500 rpm).
- Backprobe connector: verify 5 V reference present and stable, and good ground. If missing or unstable, trace wiring to ECM and repair.
- Measure sensor signal voltage while applying known pressure (if shop equipment available) or while varying engine load. Compare voltage vs expected curve from vehicle spec.
- Check continuity and resistance of the signal, power and ground circuits between sensor and ECM. Repair any opens/shorts. Perform wiggle test to find intermittent faults.
- If sensor wiring and continuity are good but signal is out of range, remove sensor, inspect probe for contamination and clean if serviceable, or replace sensor with OE or equivalent part.
- If backpressure seems high, inspect exhaust system and DPF for restriction; perform DPF diagnostic/cleaning or repair exhaust restrictions as required.
- After repairs or sensor replacement, clear codes and road test to confirm the fault does not return. If it persists, consider ECM input circuit testing or replacement per manufacturer procedures.
Likely causes
- Failed/exhaust pressure sensor
- Wiring short to voltage or ground, or open circuit
- Poor ground or low reference voltage at sensor
- Clogged DPF or restriction causing abnormal pressures
- Connector corrosion or bent pins at sensor or ECM
Fault status
Status
ECM has detected that the exhaust pressure sensor A circuit is producing values outside the expected range or is not performing correctly. The condition can trigger the MIL and may affect emission control functions and DPF regeneration.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
P0471
MERCEDES-BENZ
P — Powertrain
Exhaust Pressure Sensor Range/Performance
Views:
UK: 14
EN: 35
RU: 37
AI status
Completed
Completed
100%
Causes
- Faulty exhaust/back‑pressure sensor (sensor A)
- Open, short or intermittent wiring between sensor and ECM
- Corroded or loose connector terminals
- Poor sensor reference or ground (bad 5 V reference or ground)
- Excessive exhaust backpressure (clogged DPF, restriction)
- Mechanical damage to sensor or probe (contamination/soot)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Reduced engine performance or limp mode in some vehicles
- Elevated exhaust/backpressure readings or failed DPF regen
- Reduced fuel economy
- Increased emissions, rough idle or turbocharger control faults on turbo engines
- Related warning lights (DPF, turbo, or emission system)
What to check
- Read freeze‑frame and stored data with a scan tool; record live exhaust pressure PID and other related PIDs (MAP, turbo boost, DPF differential pressure)
- Check for additional stored codes (EGR, DPF, boost, MAP)
- Visual inspection of sensor, probe, wiring harness and connector for damage, contamination, soot, corrosion or loose pins
- Backprobe sensor connector: measure reference voltage (typically ~5 V) and ground continuity to chassis or ECM ground
- Measure sensor signal voltage while engine is cold, at idle and during revs; look for a smooth, proportionate change
- Wiggle wiring and connectors while observing live data for intermittent changes
Signal parameters
- Typical sensor type: analog pressure sensor (variable voltage output)
- Reference/supply voltage: ~5.0 V (measure 4.5–5.5 V depending on vehicle)
- Signal output: typically ~0.5–4.5 V linear with pressure (vehicle dependent)
- Expected behavior: smooth, proportional voltage change with engine speed/load; no sudden drops to 0 V or fixed high voltage
- Pressure range: depends on design — often reads vacuum to positive backpressure (example ranges: -20 kPa to +200 kPa); consult vehicle spec for exact values
Diagnostic algorithm
- Retrieve DTC, freeze‑frame and note operating conditions when fault set. Check for related codes (EGR, DPF, MAP, turbo codes).
- Perform visual inspection: sensor/probe condition, connector pins, wiring harness routing; repair any obvious damage.
- Using a scan tool, observe live exhaust pressure signal. Rev engine and watch for smooth change. Note values at key points (idle, 2500 rpm).
- Backprobe connector: verify 5 V reference present and stable, and good ground. If missing or unstable, trace wiring to ECM and repair.
- Measure sensor signal voltage while applying known pressure (if shop equipment available) or while varying engine load. Compare voltage vs expected curve from vehicle spec.
- Check continuity and resistance of the signal, power and ground circuits between sensor and ECM. Repair any opens/shorts. Perform wiggle test to find intermittent faults.
- If sensor wiring and continuity are good but signal is out of range, remove sensor, inspect probe for contamination and clean if serviceable, or replace sensor with OE or equivalent part.
- If backpressure seems high, inspect exhaust system and DPF for restriction; perform DPF diagnostic/cleaning or repair exhaust restrictions as required.
- After repairs or sensor replacement, clear codes and road test to confirm the fault does not return. If it persists, consider ECM input circuit testing or replacement per manufacturer procedures.
Likely causes
- Failed/exhaust pressure sensor
- Wiring short to voltage or ground, or open circuit
- Poor ground or low reference voltage at sensor
- Clogged DPF or restriction causing abnormal pressures
- Connector corrosion or bent pins at sensor or ECM
Fault status
Status
ECM has detected that the exhaust pressure sensor A circuit is producing values outside the expected range or is not performing correctly. The condition can trigger the MIL and may affect emission control functions and DPF regeneration.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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