What Does P2166 Mean?
The PCM has detected that Throttle/Pedal Position Sensor D is not reaching or maintaining its maximum stop position correctly. This indicates the fourth sensor in advanced multi-sensor throttle systems cannot verify proper closed throttle position.
Safety Warning
Critical safety issue compromising multiple redundant throttle position verification systems. Vehicle may exhibit severe throttle control problems, unexpected acceleration, or enter failsafe mode. Immediate repair required before normal operation.
Common Causes
45%
Failed integrated accelerator pedal position sensor assembly affecting sensor D circuit
25%
Connector or wiring fault specific to sensor D signal circuit
15%
Pedal assembly mechanical failure preventing proper rest position detection
10%
Electronic throttle control system calibration error requiring programming
5%
PCM internal fault or software corruption
Diagnostic Steps
1
Step 1: Using advanced scan tool, monitor all four APP sensor circuits simultaneously (A, B, C, D) through full pedal range to isolate sensor D malfunction pattern
2
Step 2: Inspect pedal assembly for any physical damage, obstruction, or wear that would prevent sensors from detecting true rest position
3
Step 3: Disconnect APP sensor connector and perform voltage/resistance tests on sensor D circuit per manufacturer specifications, comparing to known-good values
4
Step 4: Verify all reference voltages and grounds for sensor D circuit are within specification using digital multimeter
5
Step 5: Attempt throttle position relearn procedure; if sensor D continues to show fault, replace complete APP sensor assembly as individual sensor elements are not serviceable
Estimated Repair Cost
$250 - $900
Parts + labor, varies by vehicle and location
The PCM has detected that Throttle/Pedal Position Sensor D is not reaching or maintaining its maximum stop position correctly. This indicates the fourth sensor in advanced multi-sensor throttle systems cannot verify proper closed throttle position.
The most common cause of P2166 (Throttle/Pedal Position Sensor "D" Maximum Stop Performance) is: Failed integrated accelerator pedal position sensor assembly affecting sensor D circuit
Typical repair costs for P2166 range from $250 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Critical safety issue compromising multiple redundant throttle position verification systems. Vehicle may exhibit severe throttle control problems, unexpected acceleration, or enter failsafe mode. Immediate repair required before normal operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2166 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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