Haha when my friend got the call from the dealership to tell him what the cel code was, we happened to be smokin and it cracked us up really hard when he said " your car has a 420 code"

 

That's what I figured. Alright I'll grab one, along with a cabin filter to replace my 10yo old one. lol

 

My car still has this CEL.. lolz.

Even replaced all o2 sensors and Cat. No biggie, still gets good mileage and a little scamming the smog place by pulling the battery and driving it easy for a week or so get me to pass. Only annoying thing is the light itself.

 

Really your car STILL has this? After those many years? Just to make it clear, your exhaust system (header back) is all completely stock? It is a very common cel code for our imprezas. Im running catless right now with EL headers and custom cat back. No essence of emission cels what so ever. Never got a 420 code since I made the changes. I can let you know of a very affordable mod that might fix this issue for you.

 

I'd like to hear of that 'mod'...

 

Do you, or anyone else, happen to know the part number for the rear O2 sensor?

-Brian

 

Hahaha I know right. It is all stock exhaust parts. I had the cat replaced and the code did go away for maybe 2 months, and came back. I then replaced the 02 sensors and they did nothing. I am beginning to suspect there is an exhaust leak in the header from when the crack was welded. The reason i suspect it is cuz when I have seafoamed the car some white smoke comes up from the underside of the engine.. I'm guessing there is a leak.

It just hasnt been much a problem besides the light for me to really care

I know there are sensor "extenders" which place the sensor farther from the exhaust gas which can get rid of the code.. problem is up here (I live in Vancouver, BC) AirCare (smog check) definitely give the underside the mirror treatment looking for it.

Funny thing is.. everytime the report comes out it says "Catalaytic system not ready" because I pull the battery about a week before the test to clear the CEL.. and they let me pass with that one system in not ready status

 

^ Yea I was going to recommend a specific type of extender, but if your AirCare really does visually inspect everything, then you are cornered and limited to alternatives. Sorry to hear that! Well then I guess its just one of those bad egg problems in a batch. As long as you are passing with your method lol.

 

Would you mind sharing that info with those of us with the same problem?

-Brian

 

well, you will be illegally polluting the air, and if you happen to get caught the fines are pretty substantial, but if you don't get caught...

 

No emissions where I live.
In any case, I have a stripped head stud hole? on my header on the passenger side, that could be causing a leak and why its throwing the error. Perhaps it would behoove me to have a shop tap the hole a bit bigger and place a larger bolt in there....