Failed emissions test

[Roadtoad]

I have a 1995 A6 with ABK engine which has just failed its fast idle emissions test. The reading for Co should be equal or less than .30% but its showing .74%. Mechanic says I need a new cat. It passed the natural idle test, only failed the fast idle.
I dont want to pay for a new cat if there is another reason for the high reading at higher revs, would appreciate any feedback.

[daveo]

Hi. I had a similar situation 2 weeks ago with my AEB engine. Failed on high HC at normal and high revs. Garage recomended:

(a) lambda sensor change
(b) new CAT

It passed the retest (just!!) after a lambda sensor change.

Check/test your lamda sensor first (cost is about £65) before changing your CAT as CAt is more expensive. Good luck

[Hex69]

An Italian Tune up just before testing may help also by shifting some of the crud etc.

Try going for a good run (20 miles +) revving the engine hard once warm to near the redline.

Obviously this is on your own head and if you feeel that your car won't take it, don't do it.

HTH.