mystery exhaust problem

[gungo]

I have an Orbisoud soft exhaust.
The other day my emissions light came on. After reading a couple of posts on this site it seemed a common problem in this cold weather, so had decided to get the code cleared and see if the light came back on to see if there was a problem.
A week later I still had not had a chance to get to the garage but there was a bad smell coming from under the car when the exhaust was up to normal temperature, then a couple of days later the emissions light went out on its own.
When I look under the car there is some strange black stuff on outside of the exhaust, probably where the cat is.
If I didn't know any better (which I don't) I would say that a plastic bag got caught under the car and melted onto the exhaust as it is this kind of burning plastic smell.
Can any one come up with a better explanation or explain why this would cause the emissions light to come on.
Looking under the car I don't see or here any blowing but I am obviously a little concerned that this black stuff might have come out of the cat.
Maybe some day I will have a chance to get to a garage but the smell is slowly fading and the light is out so I am assuming it is no problem.
What do people think of this little mystery.

 

[Trophy264]

two things it prob was a plastic bag, always happens.

the other to test for a leak, dont do it to much and dont do it on a hot!
turn on the engine, the go round the back and cover the tail pipes with the palm of your hand, if it chokes and stalls, no hole! like i said its not great for the car but it answers your question.

as for the emissions light mines been doing that also.


hope this helps
Ross

 

[Jonc]

If there is a leak in the exhaust, there will be sooty deposits around the leak. I had the emissions light come light up on my car recently. Took it out for hour long blast to heat up the CAT good and proper and blow out all the crud (soot, water, unburnt fuel etc) that accumulates in the exhaust from cold days and short journeys. Result, no more emissions light (and still hasn't come on since) the following morning. I've done this twice since I've owned the car. I would say the plastic bag (if it was a plastic bag!) was coincidental to the light coming on, unless it got all wrapped up and melted in the sensor on the CAT.

 

[Renaultsport]

I have the Orb Race version and my emissions light flashes randomly, normally when stuck in traffic after just starting the car. I bought I code reader a few years back for my 172 Cup (when I was removing the cat and adding a de-cat) so I use that now and then to check for any faults. She runs fine though.

The other thing you could do is start it from cold, and look under the car to see if any condensation is coming from any joins etc...