Brief History of '91 245

July - #556 ECU failed in my '90, so I pulled the one from my '91 to verify diagnosis. Worked fine so I left it. Although Lucid was kind enough to tell me how to replace the failed circuit, I whimped out and bought a rebuilt #556 from Groton. When it arrived, I put it in the '91.

August - Fuel pump relay failed on '91. Replaced.

November - Starter failed in '91. Also charging voltage was a bit low. Went to daughter's college to trade cars to replace starter. 100 mi up the road on the way back, it set a check engine light and went open-loop. I disconnected battery to clear code. Had to do this every 60-80 miles the rest of the way home. Read out code when I got home. It was the code for the temperature sensor.

Replaced starter and voltage regulator and cleaned all grounds. Drove car to work (16 mi each way) for a couple of weeks. Every two or three days, it set a code 2-1-2 (oxygen sensor) and went open loop.

Checked wiring to oxygen sensor, brickboard had to set me straight on wiring diagram. Have heating voltage and connection to ECU. This Bosch oxygen sensor is only 1 yr old. It replaced the original sensor last year as a preventative maintenance measure only (wish I'd kept the old one).

This weekend - pulled head to replace head gasket etc. Replaced water temp sensor and oxygen sensor. Warmed it up and ran some SeaFoam through it to clean any carbon that I missed. Then replaced oil and coolant.

Car runs fine, two short trips. Then drove five miles to the office supply store and SURPRISE, check engine light. Code 2-1-2 again. This car isn't going back to college tomorrow.

What is my next move?

Thanks!!