Diagnostic Trouble Codes (DTCs)

The control module will store a diagnostic trouble code (DTC) if it detects a fault. The control module can store up to 42 diagnostic trouble codes (DTCs). If the number of diagnostic trouble codes (DTCs) exceeds ten, the five first diagnostic trouble code (DTC)s will always be saved, until erased in the workshop. The other five diagnostic trouble codes (DTCs) will be overwritten. If an eleventh diagnostic trouble code (DTC) is stored it overwrites the diagnostic trouble code (DTC) stored in the sixth position and so on.

Every diagnostic trouble code (DTC) has a counter which records the number of cycles which have been "fault-free" since the diagnostic trouble code (DTC) was stored (intermittent fault). A cycle is defined as the period from when the ignition was turned on, was then on for at least 10 seconds and then turned off. Every time the cycle runs without the control module registering the fault again, the counter increases by 1. Using the counter, it is possible to determine if the control module interprets the diagnostic trouble code (DTC) as permanent or intermittent. When the counter is at 0, the control module treats the malfunction as a permanent fault. If the counter value is greater than 0 the control module interprets this as meaning the fault is intermittent.