P0120 — Throttle Position Sensor/Switch A Circuit Malfunction
Category: Powertrain Severity: High
Updated:
DTC code P0120 means: Throttle Position Sensor/Switch A Circuit Malfunction. It falls under the "Powertrain" category, with an estimated severity of High. Common causes include worn throttle position sensor, loose or corroded connector and damaged wiring; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Worn throttle position sensor
- Loose or corroded connector
- Damaged wiring
- Failed electronic throttle body
Symptoms
- Limp mode
- Surging or erratic acceleration
- Unstable idle
- Stalling
How to diagnose it step by step
- Inspect connector and wiring.
- Watch the TPS signal while pressing the pedal (it should be smooth).
- Measure 5 V reference and ground.
- Replace the sensor or throttle body.
- Perform throttle adaptation.
How to fix it
Inspect the throttle body connector and wiring. On electronic throttles the sensor is integrated, so the whole throttle body is usually replaced and adapted.
Estimated repair cost
TPS: $40–120. Throttle body: $200–600.
Frequently asked questions
What does DTC code P0120 mean?
Throttle Position Sensor/Switch A Circuit Malfunction.
Is code P0120 serious?
Severity High. Have it checked as soon as possible, especially if it affects safety or the catalytic converter.
Can I keep driving with code P0120?
With caution: the car may lose throttle response.
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