Hey guys, a few questions...


The CEL light recently came on my wife's R56 (base model, ~70K miles), with a P0420 error. With it being literally the last day of the 8yr/80k mile cat warranty, I suggested she take it to the dealer for diagnosis, in case it's a faulty cat. They told her that the flex pipe was leaking, and that was probably the problem.


I took a look at it myself, and indeed, the joint on the downstream side of the flex pipe was not entirely sealed... The joint had a little bit of flexibility, and I can feel some exhaust coming through the joint, albeit a very small amount.


My first question is this: could this trigger a P0420, even though it's downstream from the post-cat O2 sensor? (Not to be cynical, but is it possible or likely that they said this as a delay tactic so that the cat falls out of warranty?)


Second question: Since the CEL light turned off on its own a couple days later and since there are no other symptoms, is it even necessary to repair this?


Last question: If it *is* necessary to repair this, could the joint just be re-welded, using the existing flex pipe? The dealer quoted a new flex pipe, a new screw clamp for the upsteam joint with the catalytic converter, and around three hours of labor, totaling $653. Seems like a lot.


Thanks very much!

 

I had the flex pipe on my MINI replaced for about $300. Any shop that does exhaust work can do this for you.
p.s. I never got a code, just a loud exhaust sound. If your code went away you really don't have to fix it till the noise starts to scare the neighbors.

 

Thanks, Scott, for your reply... Good to know in case replacement becomes necessary. Did they use an OEM flex pipe, or did they use whatever it is that they had on-hand? Fortunately, in my case, there is no additional noise... The joint isn't totally air-tight, but it's not at all "open"...


Look forward to any opinions on whether this could cause a P0420!


Thanks again.

 

With there being zero sensors or monitoring equipment after the #2 O2 sensor, the P0420 and flexpipe leak are unrelated.

A P0420 code is set when the first and second O2 sensor determine that the cat is no longer working effectively as it does not detect anything else wrong with that system. Whatever happens after the second O2 sensor doesn't matter in these cars as they have no 3rd O2 sensor (looking at you Jaguar/Land Rover...).

 

The shop just cut out the bad flex-pipe section and welded in a new one. I'm sure it wasn't OEM.

 

 

That's what I was thinking... Thanks for the confirmation!




Gotcha. Thanks!



Wow! That's a lot better than $653!