Throttle/Pedal Position Sensor Maximum Stop Performance
Code P2166 indicates that the Engine Control Module (ECM) has detected that the throttle or pedal position sensor signal is stuck at the maximum stop position, meaning the sensor is reporting full throttle or pedal depression when it should not. This can be caused by a faulty sensor, wiring issues, or a mechanical problem with the throttle body or pedal assembly. The ECM uses this signal to control fuel delivery and engine response, so a fault can lead to reduced power, poor acceleration, or a no-start condition.
01. Most Common Causes
- Faulty throttle position sensor (TPS) or accelerator pedal position sensor (APP)
- Short circuit or open circuit in the sensor wiring or connector
- Corrosion or damage to the sensor connector pins
- Mechanical binding or sticking of the throttle plate or pedal assembly
- Failed ECM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor acceleration or hesitation
- Engine stalling or rough idle
- No-start condition in severe cases
03. Step-by-Step Diagnosis
Step 1: Connect an OBD2 scanner and verify the code P2166. Check for additional related codes.
Step 2: Visually inspect the throttle body and pedal assembly for any obvious damage, binding, or debris.
Step 3: Test the TPS/APP sensor voltage with a multimeter. Compare readings to manufacturer specifications at idle and wide-open throttle.
Step 4: Check the wiring and connectors for shorts, opens, or corrosion. Repair or replace as needed.
Step 5: If sensor and wiring are okay, replace the TPS or APP sensor. If problem persists, test the ECM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may enter limp mode, reducing power and increasing the risk of accidents. 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 the vehicle and whether the sensor or wiring needs replacement.