History:

This is the mother-in-law's car, an 89 B230 with Bosch Fuel and ignition system. It's got about 135-140,000 and starting to display some aging. Yesterday she was driving it and, as she says, "it started to chug" (under throttle). She pulled to the side of the road and parked, not wanting to go further or try to return home and risk having it die at an inoportune time. It would idle just fine though.

I went out after work and drove it home. It ran fine, but the "Check Engine" light was illuminated. I pulled the codes and got the following (3):

2-3-1 Fuel trim (lambda control) too lean or too rich at part load

1-2-1 Faulty signal to/from Air Mass Meter

1-1-3 Fuel trim (lambda control) too lean or rich

I cleared the codes which extinguished the "Check Engine" light, drove the car again for about ten minutes which included all throttle settings, etc. No codes reappeared and it ran fine. Through all this though, I made some observations:

The engine temp guage doesn't work.

The clock doesn't work. (She says the clock quit working the last time it was at the local Volvo indy for oil change.)

Questions:

Without crawling clear under the car, I couldn't see the O2 sensor like I can on our 1990 Regina car. Where is it on the Bosch car?

Where are the engine temp sensors? (Both for the guage and for the CPU) They don't share the same sensor do they???

Is there any common components that can cause the clock and the temp guage to die? The fuel guage and all other guages/instruments seem to work OK.

Thanks for any comments/idea/help/offers to come fix it.