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Fanning A Subaru

Q. I have a 93 Subaru Legacy FWD, 2.2L, 5spd, 104K miles. My problem is the cooling fans are staying on all the time when the ignition is turned on (the Check Engine light is on also). The coolant sensor checks okay with an ohm meter (according to the Chilton repair manual). The fan relays are okay.

I also just replaced the Throttle Position Sensor (it was open). I'm not sure how long the fans have been staying on, but noticed it when I found the bad TPS. The car was running rough and sometimes didn't start easily (appeared to be flooded), but did this a few times before the Check Engine light came on. The TPS seems to have fixed this, but now I have this other problem.

I have been doing resistance checks on the some of the sensors. The oxygen sensor heater is open, but voltage is present on the signal wire back to the ECU. The MAF doesn't check exactly like the book says, but I don't know if I trust their resistance checks.

The car runs perfectly so I'm thinking whatever is causing the fans to run is also causing the Check Engine light to be on.

Any help would be appreciated.

A. Good catch on the TPS Rich. I trust you followed the adjustment procedure in the manual. It's not just a matter of replacing it, it does need to be adjusted. If you need the procedure, let me know and I'll help you out. As far as the O2 sensor heater being open, I wouldn't worry too much about that.

As for the cooling fans, I have found that most times this is caused by a bad A/C relay. One fan is for the engine cooling system and the other is for the A/C. Well actually both fans come on with the A/C. If the A/C relay is bad, then the fans think the A/C is on and both fans will run.

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