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Check engine light goes on after eng warms up, briefly. obd 1 legacy


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I just recently got this '93 legacy awd wagon. :banana: runs well, but recently the CEL light comes on for about 5 or ten minutes, usually (not consistently), and usually after driving for 5 to 10 minutes. It goes off after 10 minutes or so too.

 

I thought it might've been the o2 sensor being really old (prev owner barely passed the smog); so I swapped that for a new one yesterday. But I still noticed they CEL light coming on once today.

 

The previous owner also rep'd the MAF sensor (with a working used one).

 

What else could this be?

 

Also, anyone know what a low end OBD1 reader model is for a subaru??

 

Thanks!

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Okay, great, I came across that awesome link by browsing similar threads. That's great, the black connector worked and flashed me a code 32; this was indeed the O2 sensor.

 

So, either the code was never reset (just did a 20+ minute battery disconnect, which should clear them) or I may have some faulty wiring with the new O2 sensor.

 

Anyways, this routine is great to know. :)

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Okay, great, I came across that awesome link by browsing similar threads. That's great, the black connector worked and flashed me a code 32; this was indeed the O2 sensor.

 

So, either the code was never reset (just did a 20+ minute battery disconnect, which should clear them) or I may have some faulty wiring with the new O2 sensor.

 

Anyways, this routine is great to know. :)

 

20 minutes is NOT long enough, sorry.

 

Directins to clear memory from the same article:

ECU clear memory procedure is as follows for auto and manual transmissions:

 

1. With engine at operating temperature, turn engine off. Place gear shift lever into park (auto transmission cars only).

 

2. Locate the two ECU check connectors, for most cars they are located under the steering column and consist of a black plastic male and female connector, and a green male female connector. The exact location of the connectors varies with the different year models, but generally they are located under the steering column on the drivers side.

NOTE: sometimes they are still taped over with some small amount of plastic tape, so look hard, they will be there!

With the ignition OFF, connect black to black and green to green.

 

3. Turn on ignition, do not start the engine, (and for auto transmission, cycle the gearshift lever from park to neutral and back to park), depress the accelerator pedal to full throttle and hold for a few seconds, and then release. Start engine and then drive for at least one minute, keeping road speed above 10 mph.

 

4. At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). At this point the ECU's memory is cleared. If the check engine light does not flash, or indicates some other sequence, there is a fault present in the system, and should be checked for necessary repairs.

 

5. Once done, stop the car and turn off the engine.

 

6. Disconnect the plugs.

 

This method DOES work as long as there are no other issues needing attention. :)

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