P2119

Symptoms

• Check engine light
• reduced or delayed acceleration (vehicle lags when the pedal is pressed, especially from a stop)
• irregular or bouncing idle speed
• reduced power / limp mode
• automatic transmission may hold gears longer because the ECM misreads throttle input.

Probable causes

• 1) Carbon buildup on the throttle plate and bore (frequently cited as the top cause) - EGR and oil vapors coat the plate and can bind it
• especially when cold. 2) Faulty throttle body / internal throttle actuator motor failure. 3) Wiring or connector problems in the throttle actuator circuit (corroded, frayed, or damaged wiring causing intermittent signals). 4) Weak or broken throttle return spring letting the plate float. 5) ECM software/calibration issues or voltage supply problems.

Diagnostic steps

1. Scan for codes and record freeze frame data; note any related throttle/pedal position codes.
2. Visually inspect the throttle body and its wiring harness and connector for damage; wiggle-test the harness with the engine running to expose intermittent faults, and pay attention to the throttle body ground connection.
3. Inspect the throttle bore and plate for carbon deposits or foreign objects; clean with throttle-body cleaner if dirty.
4. Using a capable scan tool, command the throttle actuator (actuator/active test) and compare commanded vs actual throttle position in live data.
5. After cleaning or any repair, perform the throttle relearn/adaptation procedure required by the manufacturer.
6. If the plate still fails to follow commands with wiring verified good, replace the throttle body/actuator.
7. Test drive and rescan to confirm the code does not return. Treat this code as a priority: it affects throttle control and can put the vehicle in limp mode.