Throttle/Pedal Position Sensor Maximum Stop Performance
The P2166 code indicates that the Engine Control Module (ECM) has detected a malfunction in the throttle/pedal position sensor circuit related to the maximum stop position. This typically means the sensor signal is stuck at a high voltage or the sensor is not returning to its idle position properly. The ECM monitors the sensor voltage and compares it to expected values; when the voltage exceeds the maximum stop threshold, this code is set. Common causes include a faulty throttle position sensor, pedal position sensor, wiring issues, or a stuck throttle plate.
1. Most Common Causes
- Faulty throttle position sensor (TPS)
- Faulty accelerator pedal position sensor (APP)
- Wiring or connector issues in the sensor circuit
- Carbon buildup causing throttle plate sticking
- ECM software or hardware failure
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor acceleration or hesitation
- Unstable idle or stalling
- Throttle response delayed or erratic
3. Step-by-Step Diagnosis
Step 1: Connect an OBD2 scanner and verify the code P2166. Check for additional codes.
Step 2: Inspect the throttle body and pedal position sensor connectors for damage, corrosion, or loose pins.
Step 3: Using a multimeter, test the TPS and APP sensor voltage signals at idle and wide-open throttle. Compare to manufacturer specifications.
Step 4: Check for carbon buildup in the throttle body; clean if necessary.
Step 5: If sensors and wiring are okay, perform a relearn procedure or reprogram the ECM as per service manual.
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?▼
Costs range from $150 to $400 depending on the cause. Sensor replacement is typically $100-$250 for parts and labor, while throttle body cleaning or ECM reprogramming may add to the cost.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.