Throttle/Pedal Position Sensor Maximum Stop Performance
Code P2166 indicates that the Engine Control Module (ECM) has detected a malfunction in the throttle/pedal position sensor circuit, specifically that the sensor signal is stuck at or above the maximum stop voltage for an extended period. This typically occurs when the sensor fails to return to its idle position, often due to mechanical binding, electrical faults, or a defective sensor. The ECM uses this signal to determine driver demand and control throttle actuation; a fault can lead to reduced engine power or limp mode.
1. Most Common Causes
- Faulty or internally worn accelerator pedal position sensor 'F'
- Short to supply voltage (Vref) in the signal circuit of sensor 'F'
- Short circuit between signal and supply wires
- Corroded, oxidized, or damaged pins in the sensor connector
- Poor ground in the sensor circuit
- Mechanical misalignment of the sensor or accelerator pedal
- Intermittent wiring harness failure due to chafing or heat damage
- Internal PCM failure (less common, but possible)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode activated
- Poor acceleration or hesitation
- Erratic idle or stalling
3. Step-by-Step Diagnosis
Step 1: Connect an OBD2 scanner and verify the code. Check for additional related codes.
Step 2: Visually inspect the throttle body and pedal position sensor connectors for damage, corrosion, or loose pins.
Step 3: Using a multimeter, test the sensor reference voltage (typically 5V), ground, and signal voltage at idle and wide-open throttle.
Step 4: If sensor readings are out of spec, replace the throttle position sensor or accelerator pedal position sensor as needed.
Step 5: Clear the code and perform a test drive to confirm repair.
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?▼
Typical repair costs range from $50 to $150 for parts and labor, depending on whether the sensor or throttle body needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.