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DTC codes / P21xx · Fuel and air metering / P2168

P2168Throttle/Pedal Position Sensor 'F' Maximum Stop Performance

P2168 means the engine computer has detected that the throttle or accelerator pedal position sensor circuit designated 'F' is not achieving its expected maximum stop performance during a self-test. The computer commands the throttle to its full-travel limit and compares the sensor 'F' signal against the expected value, flagging the code when the signal does not reach or correctly represent that mechanical stop.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • The check engine light illuminates, often with no other noticeable symptoms.
  • The accelerator pedal may feel unresponsive or fail to reach full power during hard acceleration.
  • The vehicle may enter limp mode, limiting engine speed and power output.
  • A hesitation or stumble may occur when pressing the accelerator pedal firmly.
  • The throttle may not return to a consistent idle position after releasing the pedal.
  • In some cases, the engine may stall or refuse to start if the throttle stop is not learned correctly.

Common causes, most likely first

  1. Carbon buildup or mechanical obstruction on the throttle body bore or plate preventing full travel to the maximum stop.
  2. A faulty throttle position sensor 'F' or accelerator pedal position sensor 'F' internally worn or damaged.
  3. Damaged, corroded, or loose wiring and connectors in the sensor 'F' circuit.
  4. A throttle body actuator motor that is weak or binding, preventing the plate from reaching the stop.
  5. A misadjusted or worn mechanical stop on the throttle body or pedal assembly.
  6. An intermittent open or short in the sensor 'F' signal or reference voltage circuit.
  7. A software calibration issue in the engine control module (ECM) requiring a relearn or update.

How to diagnose and fix it

  1. Use a scan tool to read the freeze-frame data and verify the P2168 code is current, then record sensor 'F' voltage at rest and during a slow sweep to full throttle.
  2. Visually inspect the throttle body bore and plate for carbon deposits or debris, and clean them with throttle body cleaner if any obstruction is found.
  3. Check the sensor 'F' connector and harness for corrosion, pushed pins, or chafed wires, and perform a wiggle test while monitoring live data.
  4. Measure the sensor 'F' reference voltage and ground at the sensor connector with a multimeter, comparing against the manufacturer's specification.
  5. Command the throttle actuator with the scan tool through its full range and observe whether the plate reaches the mechanical stop smoothly without binding.
  6. Perform a throttle body and pedal position sensor relearn procedure using the scan tool, then clear the code and verify it does not return after a road test.
  7. If the sensor 'F' signal remains erratic or out of range after electrical and mechanical checks, replace the affected sensor or throttle body assembly and repeat the relearn.

What the maximum stop test really checks

  • The maximum stop performance test is often run only during specific key-on or idle conditions, so a code that sets intermittently may not reappear during a short test drive.
  • Carbon buildup on the throttle plate is a frequent cause that many technicians overlook because the plate may still appear to move freely by hand.
  • A weak throttle actuator motor can pass a static resistance test but fail to drive the plate to the stop under load, so live commanded sweep data is more reliable than a simple ohm check.
  • The code can be set by a sensor 'F' circuit that is electrically intact but mechanically misaligned, meaning voltage checks alone will not reveal the fault.
  • After any throttle body cleaning or replacement, a relearn procedure is mandatory on many vehicles; skipping it will often immediately reset P2168.

Can I keep driving with P2168?

You can usually drive the vehicle to a repair shop, but expect reduced engine power and avoid situations that require full acceleration, such as merging onto a highway or climbing steep grades. If the vehicle enters limp mode or the throttle feels stuck, stop driving and arrange a tow.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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