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Home / DTC / P0120 — Throttle/Pedal Position Sensor/Switch A Circuit

P0120 — Throttle/Pedal Position Sensor/Switch A Circuit

Detailed page for trouble code P0120.

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Code

P0120

Generic P — Powertrain

Throttle/Pedal Position Sensor/Switch A Circuit

Brand: Generic
Type: P — Powertrain
Views: UK: 28 EN: 60 RU: 61
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the TPS/pedal sensor A circuit
  • Poor or corroded connector or terminal at sensor or PCM
  • Faulty throttle position sensor or accelerator pedal position sensor (sensor A)
  • Bad reference voltage (5V) or ground to the sensor
  • Contaminated/damaged sensor (water ingress, debris)
  • Faulty PCM/ECM or internal driver failure

Symptoms

  • Malfunction Indicator Lamp (MIL) on (Check Engine Light)
  • Reduced engine power / limp-home mode
  • Erratic idle, hesitation, or stalling
  • Poor throttle response or surging
  • Stored related DTCs (other TPS/pedal or throttle actuator codes)

What to check

  • Read all stored codes and freeze frame data; note related/secondary codes
  • Visually inspect sensor, connector, and wiring for damage, corrosion, or loose terminals
  • Check battery voltage and charge; test while engine off and cranking
  • Backprobe sensor connector and measure reference, signal, and ground voltages with key ON and engine running as applicable
  • Wiggle harness/connectors while monitoring live data for intermittent changes
  • Compare sensor A signal to sensor B (if dual sensors) for proper correlation and opposing ramps

Signal parameters

  • Reference voltage (Vref): ~5.0 V (should be stable within ±0.2 V)
  • Sensor signal voltage (closed/throttle off): typically ~0.2–1.0 V (varies by design)
  • Sensor signal voltage (wide open/throttle): typically ~3.5–4.8 V (smooth, monotonic increase)
  • Sensor ground: near 0 V with good continuity to PCM ground
  • Correlation: if dual sensors are used, Sensor A and Sensor B should change smoothly and follow expected opposite or parallel patterns depending on design (no sudden jumps)

Diagnostic algorithm

  1. Connect a diagnostic scanner; record P0120 and any related DTCs and freeze frame data
  2. Visually inspect pedal/throttle assembly, sensor connector, and wiring for damage, corrosion, or loose terminals
  3. With key ON (engine off) backprobe sensor: verify 5V reference, signal voltage, and ground presence. Note values.
  4. Operate pedal or manually move throttle while monitoring live signal: voltage should change smoothly without stepping or dropping to 0 V
  5. If signal is out of range, trace wiring from sensor to PCM: check continuity and for shorts to battery or ground
  6. Repair any damaged wires/terminals: repair, replace connector pins, or re-pin as needed. Use proper crimping/heat-shrink.
  7. If wiring and supply voltages are correct, replace the throttle/pedal position sensor A with OEM or known-good part
  8. After repairs, clear codes, perform relearn/calibration if required by manufacturer, then road test and monitor for return of code
  9. If code returns and wiring & sensor are confirmed good, test or replace PCM as last resort (follow manufacturer diagnostics)

Likely causes

  • Damaged/loose connector or wiring harness to sensor
  • Open, short to battery, or short to ground in signal wire
  • Failed throttle/pedal position sensor (A)
  • Poor sensor ground or 5V reference supply
  • Intermittent wiring fault at harness bend or near connector

Fault status

⚠️ Status
Throttle/Pedal Position Sensor A circuit fault — signal out of expected range or poor correlation; MIL set.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0121 P0122 P0123 P0220 P0221 P2135
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Code

P0120

GWM P — Powertrain

- Throttle Position Sensor Circuit Malfunction / Switch A

Brand: GWM
Type: P — Powertrain
Views: UK: 7 EN: 8 RU: 9
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the TPS/pedal sensor A circuit
  • Poor or corroded connector or terminal at sensor or PCM
  • Faulty throttle position sensor or accelerator pedal position sensor (sensor A)
  • Bad reference voltage (5V) or ground to the sensor
  • Contaminated/damaged sensor (water ingress, debris)
  • Faulty PCM/ECM or internal driver failure

Symptoms

  • Malfunction Indicator Lamp (MIL) on (Check Engine Light)
  • Reduced engine power / limp-home mode
  • Erratic idle, hesitation, or stalling
  • Poor throttle response or surging
  • Stored related DTCs (other TPS/pedal or throttle actuator codes)

What to check

  • Read all stored codes and freeze frame data; note related/secondary codes
  • Visually inspect sensor, connector, and wiring for damage, corrosion, or loose terminals
  • Check battery voltage and charge; test while engine off and cranking
  • Backprobe sensor connector and measure reference, signal, and ground voltages with key ON and engine running as applicable
  • Wiggle harness/connectors while monitoring live data for intermittent changes
  • Compare sensor A signal to sensor B (if dual sensors) for proper correlation and opposing ramps

Signal parameters

  • Reference voltage (Vref): ~5.0 V (should be stable within ±0.2 V)
  • Sensor signal voltage (closed/throttle off): typically ~0.2–1.0 V (varies by design)
  • Sensor signal voltage (wide open/throttle): typically ~3.5–4.8 V (smooth, monotonic increase)
  • Sensor ground: near 0 V with good continuity to PCM ground
  • Correlation: if dual sensors are used, Sensor A and Sensor B should change smoothly and follow expected opposite or parallel patterns depending on design (no sudden jumps)

Diagnostic algorithm

  1. Connect a diagnostic scanner; record P0120 and any related DTCs and freeze frame data
  2. Visually inspect pedal/throttle assembly, sensor connector, and wiring for damage, corrosion, or loose terminals
  3. With key ON (engine off) backprobe sensor: verify 5V reference, signal voltage, and ground presence. Note values.
  4. Operate pedal or manually move throttle while monitoring live signal: voltage should change smoothly without stepping or dropping to 0 V
  5. If signal is out of range, trace wiring from sensor to PCM: check continuity and for shorts to battery or ground
  6. Repair any damaged wires/terminals: repair, replace connector pins, or re-pin as needed. Use proper crimping/heat-shrink.
  7. If wiring and supply voltages are correct, replace the throttle/pedal position sensor A with OEM or known-good part
  8. After repairs, clear codes, perform relearn/calibration if required by manufacturer, then road test and monitor for return of code
  9. If code returns and wiring & sensor are confirmed good, test or replace PCM as last resort (follow manufacturer diagnostics)

Likely causes

  • Damaged/loose connector or wiring harness to sensor
  • Open, short to battery, or short to ground in signal wire
  • Failed throttle/pedal position sensor (A)
  • Poor sensor ground or 5V reference supply
  • Intermittent wiring fault at harness bend or near connector

Fault status

⚠️ Status
Throttle/Pedal Position Sensor A circuit fault — signal out of expected range or poor correlation; MIL set.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0121 P0122 P0123 P0220 P0221 P2135
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P0120

HUMMER P — Powertrain

TP System Performance

Brand: HUMMER
Type: P — Powertrain
Views: UK: 16 EN: 27 RU: 37
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the TPS/pedal sensor A circuit
  • Poor or corroded connector or terminal at sensor or PCM
  • Faulty throttle position sensor or accelerator pedal position sensor (sensor A)
  • Bad reference voltage (5V) or ground to the sensor
  • Contaminated/damaged sensor (water ingress, debris)
  • Faulty PCM/ECM or internal driver failure

Symptoms

  • Malfunction Indicator Lamp (MIL) on (Check Engine Light)
  • Reduced engine power / limp-home mode
  • Erratic idle, hesitation, or stalling
  • Poor throttle response or surging
  • Stored related DTCs (other TPS/pedal or throttle actuator codes)

What to check

  • Read all stored codes and freeze frame data; note related/secondary codes
  • Visually inspect sensor, connector, and wiring for damage, corrosion, or loose terminals
  • Check battery voltage and charge; test while engine off and cranking
  • Backprobe sensor connector and measure reference, signal, and ground voltages with key ON and engine running as applicable
  • Wiggle harness/connectors while monitoring live data for intermittent changes
  • Compare sensor A signal to sensor B (if dual sensors) for proper correlation and opposing ramps

Signal parameters

  • Reference voltage (Vref): ~5.0 V (should be stable within ±0.2 V)
  • Sensor signal voltage (closed/throttle off): typically ~0.2–1.0 V (varies by design)
  • Sensor signal voltage (wide open/throttle): typically ~3.5–4.8 V (smooth, monotonic increase)
  • Sensor ground: near 0 V with good continuity to PCM ground
  • Correlation: if dual sensors are used, Sensor A and Sensor B should change smoothly and follow expected opposite or parallel patterns depending on design (no sudden jumps)

Diagnostic algorithm

  1. Connect a diagnostic scanner; record P0120 and any related DTCs and freeze frame data
  2. Visually inspect pedal/throttle assembly, sensor connector, and wiring for damage, corrosion, or loose terminals
  3. With key ON (engine off) backprobe sensor: verify 5V reference, signal voltage, and ground presence. Note values.
  4. Operate pedal or manually move throttle while monitoring live signal: voltage should change smoothly without stepping or dropping to 0 V
  5. If signal is out of range, trace wiring from sensor to PCM: check continuity and for shorts to battery or ground
  6. Repair any damaged wires/terminals: repair, replace connector pins, or re-pin as needed. Use proper crimping/heat-shrink.
  7. If wiring and supply voltages are correct, replace the throttle/pedal position sensor A with OEM or known-good part
  8. After repairs, clear codes, perform relearn/calibration if required by manufacturer, then road test and monitor for return of code
  9. If code returns and wiring & sensor are confirmed good, test or replace PCM as last resort (follow manufacturer diagnostics)

Likely causes

  • Damaged/loose connector or wiring harness to sensor
  • Open, short to battery, or short to ground in signal wire
  • Failed throttle/pedal position sensor (A)
  • Poor sensor ground or 5V reference supply
  • Intermittent wiring fault at harness bend or near connector

Fault status

⚠️ Status
Throttle/Pedal Position Sensor A circuit fault — signal out of expected range or poor correlation; MIL set.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0121 P0122 P0123 P0220 P0221 P2135
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P0120

LAND ROVER P — Powertrain

Throttle/Pedal Position Sensor A Circuit

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 9 EN: 17 RU: 27
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the TPS/pedal sensor A circuit
  • Poor or corroded connector or terminal at sensor or PCM
  • Faulty throttle position sensor or accelerator pedal position sensor (sensor A)
  • Bad reference voltage (5V) or ground to the sensor
  • Contaminated/damaged sensor (water ingress, debris)
  • Faulty PCM/ECM or internal driver failure

Symptoms

  • Malfunction Indicator Lamp (MIL) on (Check Engine Light)
  • Reduced engine power / limp-home mode
  • Erratic idle, hesitation, or stalling
  • Poor throttle response or surging
  • Stored related DTCs (other TPS/pedal or throttle actuator codes)

What to check

  • Read all stored codes and freeze frame data; note related/secondary codes
  • Visually inspect sensor, connector, and wiring for damage, corrosion, or loose terminals
  • Check battery voltage and charge; test while engine off and cranking
  • Backprobe sensor connector and measure reference, signal, and ground voltages with key ON and engine running as applicable
  • Wiggle harness/connectors while monitoring live data for intermittent changes
  • Compare sensor A signal to sensor B (if dual sensors) for proper correlation and opposing ramps

Signal parameters

  • Reference voltage (Vref): ~5.0 V (should be stable within ±0.2 V)
  • Sensor signal voltage (closed/throttle off): typically ~0.2–1.0 V (varies by design)
  • Sensor signal voltage (wide open/throttle): typically ~3.5–4.8 V (smooth, monotonic increase)
  • Sensor ground: near 0 V with good continuity to PCM ground
  • Correlation: if dual sensors are used, Sensor A and Sensor B should change smoothly and follow expected opposite or parallel patterns depending on design (no sudden jumps)

Diagnostic algorithm

  1. Connect a diagnostic scanner; record P0120 and any related DTCs and freeze frame data
  2. Visually inspect pedal/throttle assembly, sensor connector, and wiring for damage, corrosion, or loose terminals
  3. With key ON (engine off) backprobe sensor: verify 5V reference, signal voltage, and ground presence. Note values.
  4. Operate pedal or manually move throttle while monitoring live signal: voltage should change smoothly without stepping or dropping to 0 V
  5. If signal is out of range, trace wiring from sensor to PCM: check continuity and for shorts to battery or ground
  6. Repair any damaged wires/terminals: repair, replace connector pins, or re-pin as needed. Use proper crimping/heat-shrink.
  7. If wiring and supply voltages are correct, replace the throttle/pedal position sensor A with OEM or known-good part
  8. After repairs, clear codes, perform relearn/calibration if required by manufacturer, then road test and monitor for return of code
  9. If code returns and wiring & sensor are confirmed good, test or replace PCM as last resort (follow manufacturer diagnostics)

Likely causes

  • Damaged/loose connector or wiring harness to sensor
  • Open, short to battery, or short to ground in signal wire
  • Failed throttle/pedal position sensor (A)
  • Poor sensor ground or 5V reference supply
  • Intermittent wiring fault at harness bend or near connector

Fault status

⚠️ Status
Throttle/Pedal Position Sensor A circuit fault — signal out of expected range or poor correlation; MIL set.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0121 P0122 P0123 P0220 P0221 P2135
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Code

P0120

MITSUBISHI P — Powertrain

TPS(main)

Brand: MITSUBISHI
Type: P — Powertrain
Views: UK: 13 EN: 24 RU: 34
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the TPS/pedal sensor A circuit
  • Poor or corroded connector or terminal at sensor or PCM
  • Faulty throttle position sensor or accelerator pedal position sensor (sensor A)
  • Bad reference voltage (5V) or ground to the sensor
  • Contaminated/damaged sensor (water ingress, debris)
  • Faulty PCM/ECM or internal driver failure

Symptoms

  • Malfunction Indicator Lamp (MIL) on (Check Engine Light)
  • Reduced engine power / limp-home mode
  • Erratic idle, hesitation, or stalling
  • Poor throttle response or surging
  • Stored related DTCs (other TPS/pedal or throttle actuator codes)

What to check

  • Read all stored codes and freeze frame data; note related/secondary codes
  • Visually inspect sensor, connector, and wiring for damage, corrosion, or loose terminals
  • Check battery voltage and charge; test while engine off and cranking
  • Backprobe sensor connector and measure reference, signal, and ground voltages with key ON and engine running as applicable
  • Wiggle harness/connectors while monitoring live data for intermittent changes
  • Compare sensor A signal to sensor B (if dual sensors) for proper correlation and opposing ramps

Signal parameters

  • Reference voltage (Vref): ~5.0 V (should be stable within ±0.2 V)
  • Sensor signal voltage (closed/throttle off): typically ~0.2–1.0 V (varies by design)
  • Sensor signal voltage (wide open/throttle): typically ~3.5–4.8 V (smooth, monotonic increase)
  • Sensor ground: near 0 V with good continuity to PCM ground
  • Correlation: if dual sensors are used, Sensor A and Sensor B should change smoothly and follow expected opposite or parallel patterns depending on design (no sudden jumps)

Diagnostic algorithm

  1. Connect a diagnostic scanner; record P0120 and any related DTCs and freeze frame data
  2. Visually inspect pedal/throttle assembly, sensor connector, and wiring for damage, corrosion, or loose terminals
  3. With key ON (engine off) backprobe sensor: verify 5V reference, signal voltage, and ground presence. Note values.
  4. Operate pedal or manually move throttle while monitoring live signal: voltage should change smoothly without stepping or dropping to 0 V
  5. If signal is out of range, trace wiring from sensor to PCM: check continuity and for shorts to battery or ground
  6. Repair any damaged wires/terminals: repair, replace connector pins, or re-pin as needed. Use proper crimping/heat-shrink.
  7. If wiring and supply voltages are correct, replace the throttle/pedal position sensor A with OEM or known-good part
  8. After repairs, clear codes, perform relearn/calibration if required by manufacturer, then road test and monitor for return of code
  9. If code returns and wiring & sensor are confirmed good, test or replace PCM as last resort (follow manufacturer diagnostics)

Likely causes

  • Damaged/loose connector or wiring harness to sensor
  • Open, short to battery, or short to ground in signal wire
  • Failed throttle/pedal position sensor (A)
  • Poor sensor ground or 5V reference supply
  • Intermittent wiring fault at harness bend or near connector

Fault status

⚠️ Status
Throttle/Pedal Position Sensor A circuit fault — signal out of expected range or poor correlation; MIL set.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0121 P0122 P0123 P0220 P0221 P2135
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