Throttle/Pedal Position Sensor Maximum Stop Performance Issue
Code P2166 indicates that the Engine Control Module (ECM) has detected a malfunction in the throttle/pedal position sensor circuit, specifically related to the maximum stop position. This means the sensor signal is not matching the expected voltage range when the accelerator pedal is fully depressed. The issue can be caused by a faulty sensor, wiring problems, or a misadjusted throttle stop. This code often leads to reduced engine power and may trigger limp mode.
01. Most Common Causes
- Faulty throttle position sensor (TPS) or accelerator pedal position sensor (APP)
- Wiring or connector issues in the sensor circuit (shorts, opens, corrosion)
- Misadjusted or damaged throttle stop screw
- Carbon buildup on throttle body affecting sensor readings
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode activated
- Poor acceleration or hesitation when pressing gas pedal
- Erratic idle or stalling
03. Step-by-Step Diagnosis
Step 1: Connect an OBD2 scanner and verify code P2166. Check for additional codes.
Step 2: Visually inspect the throttle body and pedal position sensor wiring for damage or corrosion.
Step 3: Use a multimeter to test the TPS/APP sensor voltage at idle and full throttle (should be ~0.5V at idle, ~4.5V at WOT).
Step 4: Check throttle stop adjustment and clean throttle body if carbon buildup is present.
Step 5: If sensor readings are out of range, replace the faulty sensor and clear codes.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with P2166 as it can cause sudden loss of power or unresponsive throttle, leading to unsafe driving conditions. Limp mode may limit speed to 30-40 mph.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether the sensor or wiring needs replacement. DIY replacement can be cheaper.