Throttle/Pedal Position Sensor Maximum Stop Performance
The P2166 code indicates that the Engine Control Module (ECM) has detected a fault in the throttle/pedal position sensor circuit related to the maximum stop position. This typically means the sensor signal is stuck at or above the maximum voltage threshold, often due to a mechanical binding, electrical short, or sensor failure. The ECM uses two sensor circuits for redundancy; a discrepancy between them can trigger this code.
01. Most Common Causes
- Faulty throttle position sensor (TPS) or accelerator pedal position sensor (APP)
- Wiring issues: short to voltage, open circuit, or corrosion in the sensor harness
- Mechanical binding of the throttle plate or accelerator pedal
- ECM software or hardware failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor acceleration or hesitation
- Erratic idle or stalling
03. Step-by-Step Diagnosis
Step 1: Connect an OBD2 scanner and verify the code. Check for other related codes (e.g., P2122, P2127).
Step 2: Visually inspect the throttle body and accelerator pedal for binding, debris, or damage.
Step 3: Test the TPS/APP sensor voltage with a multimeter. Compare readings to manufacturer specifications.
Step 4: Check wiring and connectors for shorts, opens, or corrosion. Repair as needed.
Step 5: If sensor and wiring are okay, replace the TPS or APP sensor. Clear codes and test drive.
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 $150 to $400, including parts and labor. Sensor replacement is the most common fix.