Coolant Sensor Problems

• Engine coolant temperature sensors, or ECTs, monitor the engine's internal temperature. The sensor, upon detecting a temperature fluctuation, sends an electronic signal to the PCM, or powertrain control module, indicating a cold engine, an engine warming up to operating temperature, an engine operating at normal temperature or an overheating engine. A faulty ECT that fails to properly indicate a warming engine can lead to substandard fuel injector function.
  
  

Dirty Injectors

• A clogged injector, often resulting from fuel deposits in the nozzle, may fail to spray the proper amount of fuel, leading to failure after engine warm-up. Running cleaner through the injectors often dissolves the deposits and restores proper fuel injector function.
  
  

Oxygen Sensor Problems

• After an engine warms up, the fuel injection system uses a signal from the oxygen sensor, or an electronic device used to measure the level of oxygen in the fuel/air mixture, to determine how much fuel to inject. A faulty oxygen sensor can cause the fuel injector to spray less fuel or no fuel at all.