Code
P0068
Generic
P — Powertrain
MAP/MAF - Throttle Position Correlation
Views:
UK: 21
EN: 65
RU: 49
AI status
Completed
Completed
100%
Causes
- Faulty MAP, MAF or TPS sensor
- Damaged or corroded wiring or connectors (open, short, poor ground)
- Vacuum leak or intake air restriction
- Contaminated or clogged MAF sensor or air filter
- Sticky or carbon-fouled throttle body
- Intermittent sensor signal or sensor out of calibration
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
- Poor throttle response, hesitation or stumbling on acceleration
- Rough idle, surging, or stalling
- Reduced engine power or entering limp/reduced-power mode
- Higher than normal fuel consumption or drivability complaints
What to check
- Read freeze frame and live data with a scan tool; record MAP, MAF, TPS, RPM, engine load and fuel trims
- Visual inspection of MAP/MAF/TPS connectors and wiring for corrosion, breaks or pin damage
- Monitor sensor voltages/frequencies at key on and during engine operation using scan tool or multimeter
- Perform a smoke or vacuum leak test to rule out intake leaks
- Inspect and, if necessary, clean the MAF sensor and air filter
- Check throttle body for carbon build-up and free movement; perform throttle relearn/calibration if required
Signal parameters
- MAP sensor: typically 0.5–4.5 V proportional to manifold absolute pressure (vacuum → boost); should change smoothly with throttle and load
- TPS: typically ~0.2–0.8 V at closed/throttle idle and ~4.0–4.5 V at wide open throttle (varies by vehicle); signal should change smoothly with pedal movement
- MAF: output may be volts, frequency or g/s depending on design; value should increase smoothly with airflow/engine speed
- Correlation: when TPS opens, MAF should increase (more airflow) and MAP should change predictably (manifold pressure moves toward atmospheric on NA engines). Significant lag, inverse response or inconsistent scaling between these signals can trigger the code
Diagnostic algorithm
- Retrieve and record freeze frame data and all related codes. Verify P0068 is current and note operating conditions when it set (RPM, temp, throttle position).
- Visually inspect connectors and wiring for MAP, MAF and TPS. Repair any damaged wiring or loose/corroded connectors before further testing.
- With a good scan tool, monitor live data: slowly open and close the throttle and observe TPS, MAF and MAP traces. Look for smooth, proportional responses and logical correlation between sensors.
- Measure sensor reference, signal and ground circuits with a multimeter/oscilloscope (key ON and engine running). Compare to manufacturer specs. Check for intermittent signals or excessive noise.
- Perform a vacuum/smoke test to check for intake leaks that can alter MAP/MAF readings. Repair leaks and retest.
- Inspect and clean the MAF element with appropriate cleaner. Inspect air filter and intake tract for obstructions. Re-check live data after cleaning.
- Inspect throttle body for carbon build-up and ensure throttle plate moves freely. Clean and perform throttle body relearn/calibration if required by OEM procedure.
- If wiring and mechanical systems check out but sensor signals are out of range or inconsistent, replace the suspect sensor (MAF, MAP or TPS) one at a time, then clear codes and road-test.
- If problem persists after sensors and wiring are confirmed good, check for ECM software updates or intermittent ECM faults and consider module testing/reprogramming as per OEM guidance.
- After repairs, clear codes and perform a full drive cycle to confirm the fault does not return and vehicle operates normally.
Likely causes
- Wiring harness damage at sensor connector (chafing, water intrusion)
- Failed MAP or MAF sensor producing incorrect voltage/frequency
- TPS out of range or producing erratic voltage
- Intake manifold vacuum leak (vacuum hose, gasket, intake boot)
- Dirty/contaminated MAF element or blocked air intake
- Throttle plate sticking or throttle position calibration needed
Fault status
Status
P0068 — MAP/MAF - Throttle Position Correlation. The PCM has detected a mismatch between the MAP or MAF sensor signal and the throttle position sensor signal beyond expected limits.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
P0068
HUMMER
P — Powertrain
Throttle Body Airflow Performance (PCM)
Views:
UK: 13
EN: 52
RU: 32
AI status
Completed
Completed
100%
Causes
- Faulty MAP, MAF or TPS sensor
- Damaged or corroded wiring or connectors (open, short, poor ground)
- Vacuum leak or intake air restriction
- Contaminated or clogged MAF sensor or air filter
- Sticky or carbon-fouled throttle body
- Intermittent sensor signal or sensor out of calibration
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
- Poor throttle response, hesitation or stumbling on acceleration
- Rough idle, surging, or stalling
- Reduced engine power or entering limp/reduced-power mode
- Higher than normal fuel consumption or drivability complaints
What to check
- Read freeze frame and live data with a scan tool; record MAP, MAF, TPS, RPM, engine load and fuel trims
- Visual inspection of MAP/MAF/TPS connectors and wiring for corrosion, breaks or pin damage
- Monitor sensor voltages/frequencies at key on and during engine operation using scan tool or multimeter
- Perform a smoke or vacuum leak test to rule out intake leaks
- Inspect and, if necessary, clean the MAF sensor and air filter
- Check throttle body for carbon build-up and free movement; perform throttle relearn/calibration if required
Signal parameters
- MAP sensor: typically 0.5–4.5 V proportional to manifold absolute pressure (vacuum → boost); should change smoothly with throttle and load
- TPS: typically ~0.2–0.8 V at closed/throttle idle and ~4.0–4.5 V at wide open throttle (varies by vehicle); signal should change smoothly with pedal movement
- MAF: output may be volts, frequency or g/s depending on design; value should increase smoothly with airflow/engine speed
- Correlation: when TPS opens, MAF should increase (more airflow) and MAP should change predictably (manifold pressure moves toward atmospheric on NA engines). Significant lag, inverse response or inconsistent scaling between these signals can trigger the code
Diagnostic algorithm
- Retrieve and record freeze frame data and all related codes. Verify P0068 is current and note operating conditions when it set (RPM, temp, throttle position).
- Visually inspect connectors and wiring for MAP, MAF and TPS. Repair any damaged wiring or loose/corroded connectors before further testing.
- With a good scan tool, monitor live data: slowly open and close the throttle and observe TPS, MAF and MAP traces. Look for smooth, proportional responses and logical correlation between sensors.
- Measure sensor reference, signal and ground circuits with a multimeter/oscilloscope (key ON and engine running). Compare to manufacturer specs. Check for intermittent signals or excessive noise.
- Perform a vacuum/smoke test to check for intake leaks that can alter MAP/MAF readings. Repair leaks and retest.
- Inspect and clean the MAF element with appropriate cleaner. Inspect air filter and intake tract for obstructions. Re-check live data after cleaning.
- Inspect throttle body for carbon build-up and ensure throttle plate moves freely. Clean and perform throttle body relearn/calibration if required by OEM procedure.
- If wiring and mechanical systems check out but sensor signals are out of range or inconsistent, replace the suspect sensor (MAF, MAP or TPS) one at a time, then clear codes and road-test.
- If problem persists after sensors and wiring are confirmed good, check for ECM software updates or intermittent ECM faults and consider module testing/reprogramming as per OEM guidance.
- After repairs, clear codes and perform a full drive cycle to confirm the fault does not return and vehicle operates normally.
Likely causes
- Wiring harness damage at sensor connector (chafing, water intrusion)
- Failed MAP or MAF sensor producing incorrect voltage/frequency
- TPS out of range or producing erratic voltage
- Intake manifold vacuum leak (vacuum hose, gasket, intake boot)
- Dirty/contaminated MAF element or blocked air intake
- Throttle plate sticking or throttle position calibration needed
Fault status
Status
P0068 — MAP/MAF - Throttle Position Correlation. The PCM has detected a mismatch between the MAP or MAF sensor signal and the throttle position sensor signal beyond expected limits.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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