Throttle/Pedal Position Sensor Circuit Malfunction
Code P2120 indicates a problem in the throttle/pedal position sensor/switch 'D' circuit. This sensor is part of the electronic throttle control system and sends the driver's accelerator pedal position to the engine control module (ECM). The ECM uses this signal to determine throttle opening. A fault in this circuit can cause the ECM to default to a reduced power mode, limiting vehicle speed and acceleration.
01. Most Common Causes
- Faulty accelerator pedal position sensor
- Wiring or connector issues in the sensor circuit
- Corrosion or loose connections
- Failed engine control module (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power (limp mode)
- Poor acceleration or hesitation
- Erratic throttle response
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P2120 and check for other related codes.
Step 2: Visually inspect the accelerator pedal position sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage and resistance with a multimeter according to manufacturer specifications.
Step 4: If sensor and wiring are okay, check for ECM communication issues or perform a relearn procedure.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause sudden loss of throttle control or reduced power, which may be dangerous in traffic.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, including parts and labor, depending on the cause and vehicle model.