190E 1992 Check engine light

[meltedpanda]

Trying to help out someone out. This car has an O2 sensor light that is not lit but the CEL is on. Most probable cause? Can I take it to autozone or similar to check code, or is this a MB only diagnosis. I really do not know where to start, it is running fine, low idle perhaps the only thing I notice . HAs 128K on the clock

[Hirnbeiss]

Autozone can only check OBDII diagnostics (1996 and later). There is some info here on the forum about making your own code reader with about $15 in Radio Shack components - for the W124. I assume it would work on yours too, but I don't know for sure.

[slk230red]

Originally Posted by meltedpanda

Trying to help out someone out. This car has an O2 sensor light that is not lit but the CEL is on. Most probable cause? Can I take it to autozone or similar to check code, or is this a MB only diagnosis. I really do not know where to start, it is running fine, low idle perhaps the only thing I notice . HAs 128K on the clock

My '93 doesn't have a check engine light, but the CFI Control Module still stores DTC codes and I can retrieve them using one of the homemade LED testers that has been discussed on this site.
Since yours has the check engine light then it probably has the built-in LED mounted in front of the battery. Press button for 2 to 4 seconds, note readout.

1 flash = No malfunction in system
2= Throttle position switch, wide open throttle contact
3= Engine coolant temperature sensor
4= Air flow sensor potentiometer
5= Heated oxygen sensor
6= not assigned
7= TD signal
8= Barometric pressure sensor
9= Electrohydraulic actuator
10= Throttle position switch, closed throttle position contact
12= Exhaust gas recirculation temperature sensor (California models only)

[meltedpanda]

thanks SLK , will do