MPI/MPFI malfunctions and self-diagnosis (Audi A4 B5)

The MPI/MPFI control unit can detect about 30 faults in the electrical components of the ignition/injection system and store them in the computer memory. A distinction is made between permanent faults and sporadic (occasional) malfunctions. Information about sporadic faults is erased after 50 engine starts, if they have not recurred.

In the workshop, the computer with information about faults is interrogated using the VAG 1551 reading device (see chapter Regular maintenance). An amateur does not have the opportunity to conduct such a survey, therefore, if there is a suspected defect in the ignition/injection system, it is necessary to instruct the workshop to read the information about the malfunctions in the memory device.

Additionally, you can use the section Help with malfunctions at the end of the chapter, which lists many possible defects that can be detected through self-diagnosis.

For the sake of order, after repairs in the workshop, it is necessary to erase the information about faults using a reading device.

(A link to the original source is available on the website: AUDIMANUAL.ru)