Throttle/Pedal Position Sensor Circuit Low
The P2122 code indicates that the throttle/pedal position sensor or switch 'D' circuit has a low voltage input. This sensor is typically part of the accelerator pedal position (APP) sensor assembly. The ECM detects a voltage signal lower than the expected range, often due to a short to ground, open circuit, or faulty sensor. This can cause reduced engine power, poor acceleration, and in some cases, a failsafe mode.
01. Most Common Causes
- Faulty accelerator pedal position sensor
- Short to ground in sensor circuit
- Open circuit in sensor wiring or connector
- Damaged wiring harness near pedal assembly
- Corroded or loose electrical connectors
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor throttle response or hesitation
- Engine stalling or rough idle
- Inability to accelerate past a certain speed
03. Step-by-Step Diagnosis
Step 1: Connect OBD2 scanner and confirm code P2122. Check for additional codes.
Step 2: Visually inspect the accelerator pedal position sensor wiring and connector for damage, corrosion, or loose pins.
Step 3: Using a multimeter, check the reference voltage (typically 5V) and ground at the sensor connector. If missing, repair wiring.
Step 4: Test the sensor signal voltage while pressing the pedal. It should vary smoothly from ~0.5V (idle) to ~4.5V (WOT). If not, replace sensor.
Step 5: If sensor and wiring are okay, check for ECM issues (rare). Clear code and test drive.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with P2122 as it can cause sudden loss of throttle control or engine stalling, leading to unsafe driving conditions. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether the sensor or wiring needs replacement. Sensor replacement is usually straightforward.