Just thought i would post this hope it helps someone in the future.
I just bought a 940 Wagon 1993 4 cylinder. Only paid $200 for a roadworthy car and it included 3/4 tank of gas, 242,000 km. The check engine light was on and the owner had spent a small fortune with mechanics trying to work it out. He gave up on the car and i bought it. Once i got home i read the code took out the o2 sensor and cleaned it and the wiring in the engine bay. No change so i pulled out the lambda fuse and put it back in perfect no more light gone. Must of been a dirty fuse contact tripping it. The symptom i had was if i cleared the code and started the car cold check engine light would be off and would turn on once it got to the stage the thermostat opened.