P2166
Throttle/Pedal Position Sensor D Maximum Stop Performance
Throttle / pedal position
Generic OBD-II
High
What it means
P2166 means the "D" throttle or pedal position sensor is not reading correctly at its maximum (wide-open) stop — the value the ECM expects at full throttle or full pedal is out of range. Because this signal controls the electronic throttle, the fault often triggers reduced power or limp mode until the sensor or its wiring is repaired.
High
Can I keep driving? Drivable but limited — a pedal/throttle sensor fault often forces reduced-power or limp mode, so throttle response stays weak until it is repaired.
Common symptoms
What you'll notice
- Check-engine light on, often with a reduced-power or wrench warning
- Reduced power output, sometimes limp mode
- Poor or erratic throttle response and hesitation
- Unstable idle
Common causes
Most likely first
- Faulty throttle/pedal position sensor DLikely
- Open or shorted throttle/pedal sensor wiring harnessCommon
- Poor electrical connection or corrosion at the sensor connectorCommon
- Dirty or carbon-filled throttle bore affecting the plate's travel at the maximum (wide-open) stopLess often
- Faulty ECM (least likely)Less often
How to diagnose & fix
Work through it in order
- With the key on and engine off, check the sensor connector for a steady 5-volt reference and a good ground.
- Inspect the sensor wiring and connector for damage, corrosion, or loose pins.
- Watch the sensor voltage on a scan tool as you sweep the throttle/pedal to wide-open, looking for a signal that never reaches its expected maximum.
- Clean the throttle bore if carbon is limiting plate travel.
- Replace the throttle/pedal position sensor if the signal is out of spec, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2166?+
For short trips only. The ECM may cap power because it cannot trust the throttle signal, which makes merging and hills harder. Diagnose it before relying on the car.
Can I just clear P2166?+
It clears, but if the sensor or wiring is out of range the code and any limp mode return quickly. Repair the cause first.
Related codes
Often seen with P2166
Read & clear P2166 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX