Hi guys.

My service engine soon light has been going on and off intermittantly. Lately, it's been more on than off.

I changed the oxygen sensor--no fix.
So I brought it to the local mechanic, who told me that even when the engine was starting from cold, it's throwing a code 14--high temp at engine coolant temp sensor.

Long story short: he replaced the coolant temp sensor. He's saying that he now thinks the computer's fried, and that the switch that I attached that grounds out the fan relays (so I could switch the fans on whenever I want) probably did it. I've had that switch in for a year, and have used it occasionally, with no problems. He also said the Bosch 02 sensor I installed could cause problems (it's only been in for a few days).

Is his bad CPU diagnosis reasonable?

 

So code 14 was the only code it threw out? You should really get your fans back to the normal operation and use the lower fan switch. And have the chip adjusted if you have the dual fans. Im not sure if any of those things you mention mean that your cpu is bad.

 

High coolant temp means the switch, or the wire, is shorted. If it still happens after replacing the switch, then its the wire.

 

RUN don't walk as fast as you can rom that "mechanic." You need to get away from him as fast as your car can run. He is not a mechanic. If he thinks an ecm is fried because it throws one code, or that you can fry it by grounding your fan relay to keep the fans running, he is demonstrating total ignorance. He doesn't begin to have a clue how these cars work; and if let him he will proceed to change the ecm and every sensor in the car when that doesn't fix it, he will throw up his hand, but you will have spent $$$$ without replacing anything that needed replaced.

 

I've got the car back, and didn't have anything done other than the coolant temp sensor.

Anyway, I'll check it out the wire--and bypass the heater core that recently started leaking. (Wonder if the leaking heater core contributed to the problem in the first place.)

Thanks, everyone.