P0120
PowertrainThrottle Pedalhigh severityThrottle/Pedal Position Sensor/Switch A Circuit
What P0120 Means
General malfunction in the throttle position sensor (TPS) or accelerator pedal position sensor circuit.
Symptoms
- Check Engine Light
- Erratic idle
- Poor throttle response
- Limp mode
- Stalling
Common Causes
- Faulty TPS
- Wiring damage
- Throttle body issue
- PCM failure
Diagnostic Steps
- Test TPS voltage sweep (smooth transition 0.5-4.5V)
- Inspect wiring
- Check throttle body
- Test reference voltage
Where to start: Replace TPS or throttle body assembly. Some vehicles require TPS relearn procedure.
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ANCEL AD410 →
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Serious DIY~$100
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Bidirectional tests, service resets, all systems.
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Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
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