Malfunctions and Self-Diagnosis

The injection control unit can recognize and store in the fault memory exactly 30 types of faults occurring in the electronic ignition/injection system. The following is recorded: whether the fault is permanent or intermittent (occurring only from time to time). Records of intermittent faults are erased after 50 engine starts if the intermittent fault does not reappear.

Fault memory data is read in workshops using the V.A.G 1551 scan tool (see the Routine Maintenance section). The fault memory cannot be read at home, so if an ignition/injection system defect is suspected, contact a workshop to read the fault memory. You may also use the fault table at the end of this chapter, which lists numerous possible faults that go beyond self-diagnosis. After repairs, the fault memory must be cleared at a workshop.

Note: The MPFI control unit (2.6-liter engine) remains active for up to 1.5 hours after the ignition is switched off. This means that a fault occurring in the injection system during this time is also recorded in the fault memory. The connector is also recognized as a fault when it is disconnected (for example, when checking a sensor).

However, this does not mean that you have to wait 1.5 hours each time before starting repairs. Such an interruption is registered as a fault only once and therefore falls into the "bin" for intermittent faults, whose records, as is known, are erased again.