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93 Legacy L Check Engine Light code 21


whiteout628

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I've been working on this Legacy for a friend and I cannot figure it out. It is setting the check engine light for a code 21, engine coolant temperature sensor or circuit. Fail safe mode is to turn the fans on all the time. That's fine and dandy.

 

I replaced the ECT and it did not do anything. I checked the wires going to the ECT for continuity between the larger connectors on the frame rail beside the battery. Both wires have continuity. I checked for reference voltage at the ECT connector, I had 4.8something volts. I checked the coolant temperature sensor to see if the new one I got was bad. It wasn't.

 

Are there common problems with these that make this happen? What else can I check?

 

Any help is greatly appreciated!

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Tha't wierd. If the wires aren't grounded somewhere (Which they're not since you tested them), and the sensor is good, and the voltage is right where it should be then all should be well. For a while mine was doing the same thing but it somehow stopped. In the meantime (It was winter at the time) I unplugged one of the radiator fans so the car would heat up. With both those fans going full bore all the time the car would never warm up... :lol:

 

I don't know, somehow the car fixed itself. I kinda wish it would do that more often! :lol:

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I know just what you mean... my Neon just took a dump on me yesterday. The fuel pump decided it like its job any more...

 

The only wiring that I didn't get to check because I couldn't find the PCM was the other half of that larger connector and the PCM. Though, I doubt there is anything wrong with it because I got 5volts at the ECT connector.

 

Do you think a hard restart of the computer (disconnecting the negative battery cable) would do anything?

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I had this exact same problem with my '92. Check that the connector underneath the dash for the computer self test mode isn't hooked up. That was all the problem was with my car. After I disconnected the wire, I then disconnected the battery. If you do this walk away and get a beer because waiting two to five minutes (as the book suggests) does not work.

:spin::spin::spin:

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