Probable Causes:

• Loose Engine Ground
• Open E1 Circuit
• Open Injector Circuit
• Fuel Line Pressure (Blocked Injector)
• Open Or Short In Oxygen Sensors Or Circuits
• Ignition System
• Coolant Temperature Sensor
• Airflow Meter Or Air Intake System
• ECM

For oxygen sensor or circuit testing, see CODE 21 - O2 SENSOR SIGNAL test procedures in this article. For injector or circuit testing, see TEST NO. 9 - INJECTOR CIRCUIT in this article.