Fault code P0120 – a step-by-step guide to diagnosing and fixing it

Error code P0120 is displayed and the check engine light is on - what does this mean?

The DTC P0120 is triggered by the OBD/EOBD system when a problem is detected with the throttle position sensor (TPS). This fault code indicates a malfunction in the throttle position sensor circuit, which transmits the position of the throttle valve to the engine control unit.

What can cause this error code?

• Defective throttle position sensor (TPS)
• Damaged or corroded cable connections to the sensor
• Loose or dirty plug connections
• Defective throttle body
• Wear on the throttle valve shaft
• Faulty ground connection of the sensor
• Short circuit in the wiring
• Defective engine control unit (ECU)

What symptoms occur in parallel with fault code P0120?

• Irregular idling: The engine runs unevenly or stutters when idling
• Poor throttle response: Delayed or jerky response when accelerating
• Increased fuel consumption: Significantly higher fuel consumption than usual
• Starting problems: Difficulty starting the engine
• Engine stalling: Especially at low engine speeds or when idling
• Reduced engine power: noticeable loss of power while driving

How to fix the problem of trouble code P0120?

• Repairing trouble code P0120 requires a systematic approach to identify the exact cause.
• Replace the throttle position sensor: Replace the defective TPS with a new original part and carry out a basic adjustment
• Repair wiring: Check and repair damaged wiring between sensor and control unit, including insulation and continuity
• Clean plug connections: Clean all plug connections with contact spray and ensure a tight fit
• Clean throttle body: Remove deposits with special throttle valve cleaner and check mechanical function
• Check the ground connection: Check and clean all ground connections of the sensor and the engine control unit
• Replace the complete throttle body: If the throttle shaft is mechanically defective, replace the entire housing