S14roller

So I had a CEL and took it to dealer today. They stated all codes in ME were related to o2 sensors and they said it's due to the exhaust setup with no cats. Codes show up as: Signal 02 sensor, mix cylinder 1, bank 1, mix lean, and o2 sensor swap.

They seemed pretty sure nothing else was wrong in terms of air leaks, etc. Car drives normally and the only symptom I have is a very slightly rougher idle (RPMs hold, just get a slight vibration).

So my question - it seems like they think maybe putting on 02 extenders may do the trick even though a search shows no other c63 owners have done this yet. Any thoughts?

I've debated getting the 02 sensors tuned out, but my car has a tune already albeit from a tuner that is no longer in biz, so it seems like paying again for another tune isn't ideal cost wise. I may contact Eurocharged to see if there's anything they can do with the situation but wanted to get everyones thoughts on best way to resolve the CEL.

Thanks!

CarHopper

Adding an o2 spacer could do the trick. A new tune would be the "better" route, but I definitely understand not wanting to pay for a whole new tune.

I take it you're in a state w/o inspections too...

I'd start at the spacer and go from there.

itzjonjon69

curious to know who tuned your car?

S14roller

Have you heard of anyone else running spacers? It seems more common on other cars, but not much came up with a C63 search. I'm assuming the C63 is like most other cars and uses 18mm thread?

CarHopper

I have not heard of it on the C63. I had a built Sti and ran it no problem though. It is the same concept, just the majority of the c63 crowd doesn't do it. Either they live in a state that has no inspections or, if they have headers, they get high flow cats.

Likely to be 18mm, but I make no promises.

C63-AMG

I had almost the very same issue. I ended up buying 4 new sensors thinking that was the fix. Well long story short, after the exhaust had been installed, the sensors had been crossed and swapped. An indy shop was able to figure that out after an hour or so with the diag machine. I tried the o2 bung route but those messed with the readiness monitors so I removed them and within a day all monitors came ready.

CarHopper

The car is finicky to begin with. The OP doesn't have misplaced o2 sensors..

I think the hardest part of this will be to find how spaced the o2 sensors need to be in order for monitors to set.

S14roller

What codes were you getting? Curious how to tell if the sensors are crossed/swapped?

With the o2 spacers, did you just buy normal ones off amazon/ebay?

I'm OK with spacers messing with the readiness, just wouldn't mind not seeing a CEL