Basic Diagnostic Procedures

The ECM stores component failure information for the Closed Loop Emission Control system under a related trouble code. This trouble code can be recalled for diagnosis and repair.

When recalled, these codes are indicated by flashes of the "CHECK ENGINE" lamp. For example, trouble code 23 would be indicated by the "CHECK ENGINE" lamp flashing twice, a short pause, then three flashes. A long pause will follow, then the cycle will repeat 2 more times. The first series of flashes indicates first digit of the code; second series of flashes indicates the second digit of the code.

If more than one fault is stored in the memory, the lowest numbered code will flash 3 times, followed by the next highest code number, and so on, until all faults have been flashed. The faults will then repeat in the same order.