[STi&CBR]

Hey guys, I searched the forum and found out what my problem is, now I have to figure out what to do about it.

I have a highflow CAT and aftermarket exhaust (previously installed, i need to check the brand when I get out of work).

Anyway, I have the Cat Inefficiency CEL. Should I just go ahead and reset the ECU? If so, how do I do that? I drove it for about 1000 miles before this came on. Does this mean that I might just need to replace the CAT, or is it just something I'll have to deal with while using a highflow model?

Thanks for the help

[Blackfang]

Chances are the aftermarket cat isn't sufficient for the ECU programming. I have seen that in the past where new aftermarket cats set it off. Sometimes an AF/O2 sensor can set that code off too.

If you just want to reset it, go to Autozone and they will do that for you. I would just reset it and see if it comes back on.

[Nexus_One]

You need an O2 simulator, but depending on what dp you have it could be kind of difficult.

I'm running the Cobb and they placed the hole too close to the undercarriage so I can't run an O2 simulator. I'm having the same issue you are, Cobb advised me to have the code removed from the ECU using my AP2, right now I throw the code about once a week.

[Blackfang]

Originally Posted by Nexus_One

You need an O2 simulator, but depending on what dp you have it could be kind of difficult.

I'm running the Cobb and they placed the hole too close to the undercarriage so I can't run an O2 simulator. I'm having the same issue you are, Cobb advised me to have the code removed from the ECU using my AP2, right now I throw the code about once a week.

That will work too. In my position, I do not advise that for obvious reasons, but the tune on my Cobra and LS1 has them tuned out.

[STi&CBR]

Thanks guys for the info!

One interesting thing happened though... the light turned off but I still have a loss of power. Is it possible that the old CEL is still retarding the fuel injectors even though the light isn't on??? If I take it to an autozone can they still cancel the alarm? Is is possible that the CEL for cat inefficiency could be from a loose gas cap?

Sorry for the list of questions. Thanks for a response to any of the questions.

[Blackfang]

Originally Posted by STi&CBR

Thanks guys for the info!

One interesting thing happened though... the light turned off but I still have a loss of power. Is it possible that the old CEL is still retarding the fuel injectors even though the light isn't on??? If I take it to an autozone can they still cancel the alarm? Is is possible that the CEL for cat inefficiency could be from a loose gas cap?

Sorry for the list of questions. Thanks for a response to any of the questions.

The CEL Code for a loose fuel cap is a p0457, not a p0420.

[alphaSTI]

Cobb AP Stage2 maps have the P0420 code turned off. I'm not sure if you have any EM on your car right now. I would suggest going that route.

[STi&CBR]

Ok, so I was content with just getting it shut off at an Autozone whenever it comes on... but now it is a lot more frequent. The first time, I drove it for about 1500 miles before it came on, now it is coming on once or twice a week!! Does this mean that I should just replace the high flow cat with a new one? I understand that this equipment can cause that, but why would it be so much more frequent now? Autozone said it is possible that the code could be from bad spark plugs and wires causing a missfire. I think they were just trying to sell me some spark plugs and wires... Could they be right, or would that be a different code? How do I test for that?

Thanks again for the help!!!

[Blackfang]

Originally Posted by STi&CBR

Autozone said it is possible that the code could be from bad spark plugs and wires causing a missfire. I think they were just trying to sell me some spark plugs and wires... Could they be right, or would that be a different code? How do I test for that?

Thanks again for the help!!!

You would get a different CEL code then for that. They are by no means technicians so I would take what they say with a grain of salt and not likely. That is what happens when they scan things for free. It is followed up with a shopping list of parts you may not need.

Have a competant Subaru tech diagnose it

[Ying]

On my old WRX I got one of these O2 Simulator Adapter CEL Fix (Mechanical) as a temporary cheap solution. It'll pull the sensor farther out of the exhaust flow, but you really need to get some engine management. That would do less damage to your motor over the long haul.

[StylesJim]

You need engine management. You are hurting your car and wasting power at the same time. First off... I would probably stop resetting the ECU. There is a reason it keeps flashing a CEL. CELs are BAD and are not supposed to be ignored.

For an easy solution... stop resetting the ECU, spend a chunk of change on a Cobb Accessport (CobbTuning.com - Home Page) and flash to stage 2. To simplify, it will allow your car to run the way it should with a turbo back exhaust (downpipe and catback). These cars require some form on engine management/tuning to run properly with power modifications.

If I were you I would probably take it easy on the car until then.