Over the summer I had an error message saying my fuel cap wasn't closed properly. I had a full service in September and no fault could be found. I now have an anti-pollution system fault on the dashboard but the car seems to be running fine.

Peugeot dealers are charging £89 for diagnostic testing and now want around £400 to replace "cap signal sensor for additive ecu". Not sure what to do. Can anyone advise as it seems crazy money.

London1111, November 2011

Maybe a magnet has come out of the cap so the sensor doesn't sense that it is there anymore.

Have a read here:
http://www.honestjohn.co.uk/forum/post/index.htm?t=59532

You'll see that someone else had a similar problem and it turned out to be the vacuum hoses that come out of the EGR unit that can come loose. (the last post on the above thread).

£400 for a new cap seems a trifle expensive. Haven't you got a decent Peugeot indy with a good reputation near you that you could try?

ChicksFan, December 2011

Get an obd reader from ebay, plugs into a laptop, OR some stand alone readers available, Halfords do one That would save you about £60 for the diagnostics. Then read the codes your self, It will point you in the correct direction for the fault, then DIY or a local garage, would be cheaper. Main dealers no longer have the sole rights to do a service, other garages can, and are allowed to stamp the book to maintaind service record, as long as they follow the guide, I found they follow the guide Better than the dealers, so you get a better job done for less. Kwick fit and such type of places.

SD, November 2011