BMW E36 reading and clearing fault codes
How do I read fault codes on an E36?
The Euro E36 has no check engine light, and an ordinary OBD reader does not work. The codes are read with an ADS cable and an old BMW diagnostic program such as DIS. The engine management, ABS and airbag codes can often also be read with an INPA USB cable; newer modules require an ADS cable.
Why does the diagnostic tool not connect to my E36?
One faulty control unit connected to the bus, such as the ABS, the instrument cluster or the engine management, can bring down the whole diagnostic connection. Disconnect the units one at a time and try again. Sometimes briefly disconnecting the battery also helps.
How do I clear the E36 fault memory?
The right way is a diagnostic program or diagnostic tool. Without a tool the memory has been cleared by disconnecting the battery or by connecting the disconnected battery terminals to each other for 10-30 minutes. Clearing does not fix the fault: if the cause still exists, the code returns.
Why does my E36 have a fault but no fault code?
The mass air flow sensor and the crankshaft position sensor can fail gradually and give plausible but wrong values, in which case no code is set. The fault may show only in live data or as an unstable idle. Do not rule out a component just because there is no code.