Trouble Code Descriptions

The ``Check Engine'' light will only come ON if a malfunction exists. It takes up to five seconds minimum for the light to come ON when a problem occurs. If the malfunction clears, the light will go out and a trouble code will be stored in the ECM. A code 12 will not be stored in the ECM memory. If the light comes ON intermittently, but no code is stored, refer to Driver Comments (Symptom Diagnosis). Any codes stored will be erased if no problem reoccurs within 50 engine start-ups. The trouble codes indicate specific problems as follows:
Trouble Code 12 (This Code Will Not Be Stored) - No distributor reference pulse to the ECM and will only flash while the fault is present.
Trouble Code 13 (Oxygen Sensor Circuit) - The engine must operate for approximately two minutes at part throttle and under road load, before this code will be stored.
Trouble Code 14 (Shorted Coolant Sensor Circuit) - The engine must operate for approximately two minutes before this code will be stored.
Trouble Code 15 (Open Coolant Sensor Circuit) - The engine must operate approximately 5 minutes before this code will be stored.
Trouble Code 21 - Incorrectly adjusted idle switch and/or open circuit. This code will be stored if engine speed decreases below 600 RPM for longer than 32 seconds. If the throttle position sensor and idle switch are faulty or incorrectly adjusted, this code will be stored.
Trouble Code 22 - Fuel cut-off relay and/or circuit open.
Trouble Code 23 - Open or grounded mixture control solenoid circuit.
Trouble Code 42 - Fuel cut-off relay and/or circuit shorted.
Trouble Code 44 - (Lean Oxygen Sensor Condition) - The engine must operate for approximately two minutes at part throttle and under road load before this code will be stored. The code will not be stored when coolant temperature is below approximately 158°F and/or the air temperature within the air cleaner is below 32°F in a low altitude condition. This code will not be stored in a high altitude condition.
Trouble Code 45 (Rich System Indication) - The engine must operate for approximately two minutes at part throttle and under road load, before this code will be stored. This code will not be stored when engine speed is other than 1500-2500 RPM and/or the coolant temperature is below 158°F or vehicle is being operated at high altitude.
Trouble Code 51 - Indicates that the calibration unit (PROM) is defective or incorrectly adjusted. It takes up to 30 seconds before this code will be stored.
Trouble Code 54 - Shorted mixture control solenoid circuit and/or faulty ECM.
Trouble Code 55 - Faulty ECM and/or problem with A/D converter in ECM.