reset AUDI A8 1999 D2 / 1.G AHA Engine On Board Diagnostic Workshop Manual

01-1


On Board Diagnostic (OBD)

Function

The Multiport Fuel Injection (MFI) system is
equipped with an Engine Control Module (ECM) -
J220- with On Board Diagnostic (OBD)
capability.
When malfunctions occur in sensors or
components monitored by OBD, Diagnostic
Trouble Codes (DTC) are stored in DTC
memory.
Stored DTCs are identified using the VAG1551
Scan Tool (ST) page 01
-16
.
After the necessary repairs are completed, DTC
memory must be erased page 01
-49
.
OBD II legal regulations require a display
(readiness code) that shows inspection
readiness for the annual exhaust emissions test.
The readiness code shows that every component
and/or system that affects exhaust emissions,
which can lead to the Malfunction Indicator Lamp
(MIL) being switched on, has been operated at
least once with positive results.
The readiness code is reset and/or erased and
must be regenerated every time DTC memory is
erased, the power supply to the ECM -J220- is
interrupted (example: when connecting
Pa
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gnostic
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