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P2121 — Throttle/Pedal Position Sensor/Switch D Circuit Range/Performance

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P2121

Generic P — Powertrain

Throttle/Pedal Position Sensor/Switch D Circuit Range/Performance

Brand: Generic
Views: UK: 33 EN: 118 RU: 36
AI status
Completed
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Completed 100%
Page language: EN

Causes

  • Faulty accelerator pedal position (APP) or throttle position sensor (TPS) D
  • Damaged, corroded or loose connector at the sensor or ECM
  • Open, shorted or high-resistance wiring in the signal, reference or ground circuits
  • 5V reference or signal ground fault
  • Mechanical binding in pedal assembly or throttle body linkage
  • Contaminated or failed electronic throttle control (ETC) module/ECM

Symptoms

  • Malfunction Indicator Lamp (MIL)/Check Engine Light ON
  • Reduced engine power / limp mode
  • Poor or delayed throttle response, hesitation or surging
  • Unintended high or low idle in some cases
  • Possible engine stall or inability to accelerate normally

What to check

  • Read and record DTC(s) and freeze-frame data with a scan tool
  • Check for other related codes (other APP/TPS or ETC codes)
  • Visually inspect sensor connector and wiring for damage, corrosion, or pin push-out
  • Backprobe and measure sensor signal, 5V reference and ground with a multimeter/scan tool
  • Compare live sensor voltage/position data to other pedal/throttle sensors for correlation
  • Wiggle harness and connector while observing live data for intermittent faults

Signal parameters

  • 5 V reference present at sensor connector (typical)
  • Signal voltage varies with pedal/throttle position and should be stable and linear
  • Typical idle/rest signal approximately 0.5–1.5 V (varies by manufacturer)
  • Typical wide open throttle signal approximately 3.5–4.5 V (varies by manufacturer)
  • No sudden jumps, stuck values, or signals outside manufacturer-specified ranges — consult service manual for exact values and sensor output behavior

Diagnostic algorithm

  1. Connect a scan tool, read freeze-frame and live data. Note sensor D voltage/position and any related codes.
  2. Inspect the sensor connector and wiring harness for damage, corrosion, water intrusion, and secure fit.
  3. Verify 5V reference and ground at the sensor with ignition ON. If 5V or ground missing, trace back to ECM.
  4. With backprobe, measure sensor D signal at rest and while operating pedal/throttle. Confirm signal changes smoothly and stays within expected range.
  5. Compare sensor D output to the other APP/TPS channels (if present) to check for correlation or inverse relationship as specified by the vehicle.
  6. Wiggle test harness and connector while monitoring live data to find intermittent faults.
  7. If wiring, reference, and ground check good but signal abnormal, disconnect sensor and check for code change or substitution test with known-good sensor if available.
  8. Repair or replace damaged wiring, connector, or sensor as indicated by tests. Secure and protect harness from future damage.
  9. Clear codes, perform relearn/calibration procedures if required by the manufacturer, then road test and re-scan to confirm repair.
  10. If fault persists after sensor and wiring verified, consider ECM/ETC module fault and refer to manufacturer diagnostics or module testing procedures.

Likely causes

  • Corroded/loose sensor connector or pin
  • Broken or chafed wiring to the sensor (open or short to ground/power)
  • Failed APP/TPS D sensor
  • Poor ground or weak 5V reference from ECM
  • Throttle body or pedal mechanical issue causing out-of-range signal

Fault status

⚠️ Status
PCM detected that Throttle/Pedal Position Sensor/Switch D signal is outside expected range or inconsistent with other position sensors.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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Code

P2121

HUMMER P — Powertrain

Accelerator Pedal Position (APP) Sensor 1 Performance

Brand: HUMMER
Views: UK: 19 EN: 73 RU: 21
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty accelerator pedal position (APP) or throttle position sensor (TPS) D
  • Damaged, corroded or loose connector at the sensor or ECM
  • Open, shorted or high-resistance wiring in the signal, reference or ground circuits
  • 5V reference or signal ground fault
  • Mechanical binding in pedal assembly or throttle body linkage
  • Contaminated or failed electronic throttle control (ETC) module/ECM

Symptoms

  • Malfunction Indicator Lamp (MIL)/Check Engine Light ON
  • Reduced engine power / limp mode
  • Poor or delayed throttle response, hesitation or surging
  • Unintended high or low idle in some cases
  • Possible engine stall or inability to accelerate normally

What to check

  • Read and record DTC(s) and freeze-frame data with a scan tool
  • Check for other related codes (other APP/TPS or ETC codes)
  • Visually inspect sensor connector and wiring for damage, corrosion, or pin push-out
  • Backprobe and measure sensor signal, 5V reference and ground with a multimeter/scan tool
  • Compare live sensor voltage/position data to other pedal/throttle sensors for correlation
  • Wiggle harness and connector while observing live data for intermittent faults

Signal parameters

  • 5 V reference present at sensor connector (typical)
  • Signal voltage varies with pedal/throttle position and should be stable and linear
  • Typical idle/rest signal approximately 0.5–1.5 V (varies by manufacturer)
  • Typical wide open throttle signal approximately 3.5–4.5 V (varies by manufacturer)
  • No sudden jumps, stuck values, or signals outside manufacturer-specified ranges — consult service manual for exact values and sensor output behavior

Diagnostic algorithm

  1. Connect a scan tool, read freeze-frame and live data. Note sensor D voltage/position and any related codes.
  2. Inspect the sensor connector and wiring harness for damage, corrosion, water intrusion, and secure fit.
  3. Verify 5V reference and ground at the sensor with ignition ON. If 5V or ground missing, trace back to ECM.
  4. With backprobe, measure sensor D signal at rest and while operating pedal/throttle. Confirm signal changes smoothly and stays within expected range.
  5. Compare sensor D output to the other APP/TPS channels (if present) to check for correlation or inverse relationship as specified by the vehicle.
  6. Wiggle test harness and connector while monitoring live data to find intermittent faults.
  7. If wiring, reference, and ground check good but signal abnormal, disconnect sensor and check for code change or substitution test with known-good sensor if available.
  8. Repair or replace damaged wiring, connector, or sensor as indicated by tests. Secure and protect harness from future damage.
  9. Clear codes, perform relearn/calibration procedures if required by the manufacturer, then road test and re-scan to confirm repair.
  10. If fault persists after sensor and wiring verified, consider ECM/ETC module fault and refer to manufacturer diagnostics or module testing procedures.

Likely causes

  • Corroded/loose sensor connector or pin
  • Broken or chafed wiring to the sensor (open or short to ground/power)
  • Failed APP/TPS D sensor
  • Poor ground or weak 5V reference from ECM
  • Throttle body or pedal mechanical issue causing out-of-range signal

Fault status

⚠️ Status
PCM detected that Throttle/Pedal Position Sensor/Switch D signal is outside expected range or inconsistent with other position sensors.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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Code

P2121

MITSUBISHI P — Powertrain

APS(main) range

Views: UK: 21 EN: 69 RU: 20
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty accelerator pedal position (APP) or throttle position sensor (TPS) D
  • Damaged, corroded or loose connector at the sensor or ECM
  • Open, shorted or high-resistance wiring in the signal, reference or ground circuits
  • 5V reference or signal ground fault
  • Mechanical binding in pedal assembly or throttle body linkage
  • Contaminated or failed electronic throttle control (ETC) module/ECM

Symptoms

  • Malfunction Indicator Lamp (MIL)/Check Engine Light ON
  • Reduced engine power / limp mode
  • Poor or delayed throttle response, hesitation or surging
  • Unintended high or low idle in some cases
  • Possible engine stall or inability to accelerate normally

What to check

  • Read and record DTC(s) and freeze-frame data with a scan tool
  • Check for other related codes (other APP/TPS or ETC codes)
  • Visually inspect sensor connector and wiring for damage, corrosion, or pin push-out
  • Backprobe and measure sensor signal, 5V reference and ground with a multimeter/scan tool
  • Compare live sensor voltage/position data to other pedal/throttle sensors for correlation
  • Wiggle harness and connector while observing live data for intermittent faults

Signal parameters

  • 5 V reference present at sensor connector (typical)
  • Signal voltage varies with pedal/throttle position and should be stable and linear
  • Typical idle/rest signal approximately 0.5–1.5 V (varies by manufacturer)
  • Typical wide open throttle signal approximately 3.5–4.5 V (varies by manufacturer)
  • No sudden jumps, stuck values, or signals outside manufacturer-specified ranges — consult service manual for exact values and sensor output behavior

Diagnostic algorithm

  1. Connect a scan tool, read freeze-frame and live data. Note sensor D voltage/position and any related codes.
  2. Inspect the sensor connector and wiring harness for damage, corrosion, water intrusion, and secure fit.
  3. Verify 5V reference and ground at the sensor with ignition ON. If 5V or ground missing, trace back to ECM.
  4. With backprobe, measure sensor D signal at rest and while operating pedal/throttle. Confirm signal changes smoothly and stays within expected range.
  5. Compare sensor D output to the other APP/TPS channels (if present) to check for correlation or inverse relationship as specified by the vehicle.
  6. Wiggle test harness and connector while monitoring live data to find intermittent faults.
  7. If wiring, reference, and ground check good but signal abnormal, disconnect sensor and check for code change or substitution test with known-good sensor if available.
  8. Repair or replace damaged wiring, connector, or sensor as indicated by tests. Secure and protect harness from future damage.
  9. Clear codes, perform relearn/calibration procedures if required by the manufacturer, then road test and re-scan to confirm repair.
  10. If fault persists after sensor and wiring verified, consider ECM/ETC module fault and refer to manufacturer diagnostics or module testing procedures.

Likely causes

  • Corroded/loose sensor connector or pin
  • Broken or chafed wiring to the sensor (open or short to ground/power)
  • Failed APP/TPS D sensor
  • Poor ground or weak 5V reference from ECM
  • Throttle body or pedal mechanical issue causing out-of-range signal

Fault status

⚠️ Status
PCM detected that Throttle/Pedal Position Sensor/Switch D signal is outside expected range or inconsistent with other position sensors.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

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