Fault
Stuck valve timing actuator
The cam phaser binds so valve timing no longer follows the commanded position.
Engine / drivability
Faults
Fault
Dirty air flow sensor
Deposits on the sensing element slow its response and bias the airflow reading low.
Fault
Failed ignition coil
Coil winding insulation breaks down under heat and load so the secondary cannot sustain the spark voltage.
Fault
Air leak at the inlet manifold
The manifold gasket no longer seals so unmetered air enters downstream of the airflow sensor.
Fault
Blocked valve timing oil passage
Sludge restricts the oil feed to the cam phaser so it cannot move as commanded.
Fault
Worn spark plug
The electrode gap has widened with use so the required firing voltage exceeds what the coil can deliver.
Fault
Blocked fuel injector
Deposits restrict the injector nozzle so the delivered fuel quantity and spray pattern fall below specification.
Fault
Failing fuel pump
Pump wear reduces delivered flow and pressure so the engine starves under load first and at idle later.
Fault
Oxygen sensor heater failure
The sensor heater circuit is open so the sensor takes too long to reach operating temperature.
Fault
Throttle sensor reading wrong
The throttle position signal has drifted so the module's idea of throttle opening is wrong.