Raikiri

iTrader: (21)

So after all the trouble of getting my car fixed for those of you who have read my other thread... I now got the CEL P0420 (bank 1)

I'm not really sure what could be causing it since all the parts are basically new... the RRM header/dp and the Magnaflow HF Cat... Could one of my 02 sensors have gone bad? I called RRM and they said just throw the CEL Eliminator on it and it should help but I'm not sure really what to do... Should I reset the ECU and let it learn or what?

I've searched through the threads but haven't really found an answer to the question on how exactly its been solved

joeyj

This code is saying that the difference between the front and rear o2 sensors are so similar, the cat is beyond its efficiency point.

Most common reasons are:
cat deteriorated
o2 sensor failed
exhaust leak
ecu failed

I'd say reset ecu to make sure it isnt a fluke first of all, and get under the car to make sure nothing is leaking.

Raikiri

iTrader: (21)

i dont understand how the cat could've deteriorated since its basically new.... i guess i can check for leaks... does that mean just make sure everything is nice and tight?

how do i know if the o2 sensor fails?

otter

iTrader: (14)

A highflow cat doesn't filter as much as the OEM cat does, so you can still throw a 420 with a HF cat. Put some anti-foulers on the rear O2 sensor (18mm, two of them stacked, drill out the top one with a 1/2" bit), should get rid of the code for you.

Raikiri

iTrader: (21)

I see... so would putting the CEL eliminator like RRM said on the first O2 sensor not really help?

otter

iTrader: (14)

Um, I really hope you didn't put one on the first O2 sensor. It goes on the second sensor.

Raikiri

iTrader: (21)

Oh... well I put it on the first O2 sensor because thats what people were telling me on the other thread for the RRM Header but I guess I can put it in the 2nd O2 sensor then... I had it taken off when my car was being repaired... but I'll try the 2nd O2 sensor today since it's going back to that same shop... Is it bad if it goes on the first O2? Please tell me I didnt break something again...

Raikiri

iTrader: (21)

Sorry I'm having a stupid moment here... by 2nd O2 sensor you mean the one after the cat right?

cubenoob

iTrader: (1)

I was throwing the same code after I put on the Header/Downpipe/High Flow Cat from RRM. The CEL eliminator that came with the header fixed the problem for me. They put it on the one after the cat and I haven't had any issues since then.

Raikiri

iTrader: (21)

all right cool well I just got the car back from the shop in order to get some work done and they put the eliminator in and the code went away... the only thing they said was that the eliminator or sensor didn't screw in deep enough so that it'd be a tight seal so they had to put spacers in there to seal it up right or something.. hopefully the code doesnt come back

otter

iTrader: (14)

Yes, after the cat. By putting it on the front one, you're pulling the sensor the ECU needs to determine if it's using the right amount of fuel out of the exhaust stream, which would likely cause it to start dumping more fuel into the engine. No harm, other than burning up a lot of excess gas.

bruce988jl

iTrader: (56)

Exactly what otter said. I did the antifouler method and occassionally still get the code but a simple reset fixes alla that. Now I'm just having problems with my LC-1 sensor going AWOL even after repeated calibrations.

Raikiri

iTrader: (21)

I just hope that I don't happen to get the code right before I go for emissions testing because I think as long as they see the light they fail you

Raikiri

iTrader: (21)

for some reason I keep getting this code after like a hundred miles of clearing the code... its getting quite annoying... i have the cel eliminator on... the shop said something about it not going in deep enough to ensure a tight fit

could it be related to that? any other suggestions as to what else could be dropping this code?

otter

iTrader: (14)

Are you using anti-foulers or RRM's cel eliminator? I've heard, in the past, that RRM's eliminator isn't long enough. Try buying a couple 18mm anti-foulers, drill one out with a 1/2" drill bit, screw them together, then screw the O2 sensor into that.