TunerPro User Forum

I've got an issue with a Bosch Motronic M3.3.1, it keeps throwing a 1211 error but the car starts and runs absolutely fine. Can anyone give me some tips or tricks on how to track down what could be causing it? The ECU itself doesn't appear to have failed as it is running fine, it seems like it maybe something like a checksum error?

Hello

https://www.e30zone.net/e30wiki/index.p ... ault_Codes
1211
DME Control Unit
DME, Motronic computer, related fault - which may indicate problem with car computer itself. Delete any stored codes and perform following test: Start the car and let it run for 30 seconds; Turn off car and let it sit for another 30 seconds; Perform diagnostic test again; If the same flash code re-appears DME should be replaced

Anyway, have you tested another bin file or ori chip?

I've cleared the code a few times by disconnecting the battery, but I'll try your method to. The code comes back after 2 - 3 starts.

No haven't tried a different bin file or chip, how could I go about trying either?

M3.3.1 calculates checksum after ignition is switched off, i think it is pretty last thing before the main relay is released. But if you put ignition back before calculation is performed, the fault code doesn't appear.

Some chip tuners leaves wrong checksum for workshops etc.., for a sign of modified BIN. ...if checksum error doesn't affect anything.

Ok that makes sense, is there an easy way for me to check my checksum? I would prefer to remove the error if I could easily. That way when the check engine light comes on I know it's for something serious!

In theory it is possible to get BIN out from ecu through K-line, but easiest way is take EPROM-chip out and read it with eprommer. That way you can check the checksum and compare bin to original or other original one. There is several different stock chips in M3.3.1, depends on which car and engine it is in.

Ok I'll look to remove the chip. Any recommendations on a good eprommer to use?

The car is a 1993 BMW 325i has the M50B25TU motor in it.

I have a spare DME now, so can check that one also.

I have TL866ii programmer. Works fine.

guys do you know or have any software to diag codes from thoose obd1 ecu's ? and if i need any interface ??