S4 Heli

Hey guys.

So... bottomed out pretty good the other day. Very soon after, got a flashing CEL then a solid CEL and some serious groaning from the exhaust... definitely a new leak.

Heres my question, the leak is just in front of the rear cat. At that mesh flex joint (in the picture). Would an exhaust leak here throw a code and cause the CEL ????? something to do with the O2 sensors? or should i be looking for something else that threw the code.

Thanks guys...

complacentsee

That should not have caused a flashing CEL. Flashing means miss fires, and is supposed to be a sign to stop driving.

You really should get it scanned to figure out whats going on. Autozone/ect can do this for free. (they can only scan for engine codes though)

An exhaust repair shop could put in a new flex.

S4 Heli

Had it up on jacks and the flex joints are leak'n pretty bad. I replaced the TTB and the DV about a month ago so i'm pretty sure their good on the pressure test.

I'm getting the exhaust fixed on monday, but the scan will have to wait for about a week. No VAG-Com here.

is there any way that the leak'n exhaust causes the O2 sensor and thus a fuel/air problem, then maybe lead to a "misfire" code? lol. Am i stretching here?

complacentsee

No chance that the leak is causing a fuel/air problem. The rear O2s can throw a code. But are not used for fueling.

donromani

I think a leak before the secondary sensor could mess with the fuel/air ratio

complacentsee

It can't. Only used for emissions purposes.