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00 Legacy GT ECU code deciphering (Please help!)

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My check engine light just came on at about 82K miles. I had a 93 Legacy that had a different method of checking engine codes and couldn't be read by a code reader. Are the newer models the same way or can they be read by a code reader? Also, saw something mentioned here about O-rings in the valve covers that keep engine oil out of spark plug holes. Any other info on those, as I have oil leaking around spark plug wires too.

Had my first experience with the check engine light around the same mileage in my 2000 legacy and turned out to be the knock sensor.

  • Author

Okay, did some searching and found I could have the code read. Took it to my local Autozone and the results are as follows:

 

P04020

Catalyst system efficiency for bank 1 is below threshold for the current engine operating condtions.

 

Can someone translate this for me?

  • Author
Okay, did some searching and found I could have the code read. Took it to my local Autozone and the results are as follows:

 

P04020

Catalyst system efficiency for bank 1 is below threshold for the current engine operating condtions.

 

Can someone translate this for me?

 

Anyone?

saw something mentioned here about O-rings in the valve covers that keep engine oil out of spark plug holes. Any other info on those, as I have oil leaking around spark plug wires too.

Seeing is believing. Mine were replaced under an extended warranty. Not sure of the cost. I guess they had to do valve cover gaskets and the spark plug seals at the same time.

Had my first experience with the check engine light around the same mileage in my 2000 legacy and turned out to be the knock sensor.

 

Any issues since then?

  • 1 month later...

Either the catalyst has been poisoned, the mixture is too rich, one of the cylinder banks is misfiring, or most likely the O2 sensors are fouled.

  • Author
Either the catalyst has been poisoned, the mixture is too rich, one of the cylinder banks is misfiring, or most likely the O2 sensors are fouled.

 

How should I start in repairing it?

  • Author

How can I further diagnose this problem? I've ran the codes, and apparently narrowed it down a bit.

 

I miss the easy stuff like rebuilding blocks and changing timing belts. Damn computers make it a lot harder to work on these things lately.

Like it was explained above, it could be a lot of things, need to test O2 sensors, cat, or even exhausts for leaks, if you want to do it yourself, get yourself a factory manual.

Also, this should be covered by federal emission waranty, check if you are still covered.

You can also reset the code and hope it wont come back.

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