Throttle/Pedal Position Sensor Circuit Low Input
The P2122 code indicates that the Engine Control Module (ECM) has detected a low voltage signal from the throttle/pedal position sensor or switch circuit. This sensor is critical for determining driver demand and throttle position. A low voltage condition can be caused by a faulty sensor, wiring issues (short to ground, open circuit), or a poor connection. This can lead to reduced engine power, limp mode, or stalling.
1. Most Common Causes
- Short to ground in the APP sensor 'D' signal circuit
- Short to ground in the sensor reference voltage (VREF) circuit
- Open circuit in the sensor power or signal wire
- Faulty or worn accelerator pedal position (APP) sensor
- Corroded, damaged, or bent pins in the sensor connector
- Internal ECM/PCM failure (less common)
2. Symptoms You Will Notice
- Check Engine Light on
- Reduced engine power or limp mode
- Poor acceleration or hesitation
- Engine stalling or rough idle
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Using a multimeter, check the sensor reference voltage (typically 5V) and ground at the connector.
Step 4: Test the sensor signal voltage while pressing the accelerator pedal; it should vary smoothly from ~0.5V to ~4.5V.
Step 5: If signal is missing or erratic, replace the sensor. If wiring is faulty, repair as needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. The vehicle may enter limp mode, limiting speed and acceleration, which can be dangerous in traffic. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically between $50 and $150 for parts and labor, depending on the sensor cost and accessibility.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.