Pre-cat Lambda sensors for the 2.7 biturbo

[robin_coxie]

I have a 2003 C5 Avant Quattro 2.7T manual, with the BES engine, around 104,000 miles covered from new. Many thanks to everyone who has helped me with advice and guidance over the past 3 years already.

Last year a succession of erratic check engine lights leading to poor fuel consumption and erratic idling were identified as the N80 valve and the coolant sensor in succession. Both replaced, CEL went away, fuel consumption improved (24 back to 26mpg average on short journeys) but still not back to where it was previously (high 28s - all numbers on the computer readout). It was suggested that the front lambda sensor pair may also be coming up for renewal. The light came on yesterday again, (and idling is a bit uneven again) and as the mileage is around the level I've read online is the service life of lambda sensors, it seems plausible that I need to get a pair fitted. I should stress that I haven't got the code read yet.

I want to get Bosch if possible; but the problem is which model - A6 2.7T BES engined cars (ie non-Allroad) don't seem to feature in many online supplier catalogues, so broadening the search slightly for other related 2.7T engines (S4, Axx-engined 230bp A6 2.7s, Allroad) from 1998 to 2004 I have found various online suppliers but there seem to be an enormous number of different versions recommended with anywhere between 50cm, 55cm, 75cm and 1.7-metre long leads. The longest appear to be the post-cat? I also found other online "DIY" guides on the 2.7t for these quoting other model numbers that appear to be compatible but intended for Citroen family cars (and consequently quite cheap).

Any suggestion of a good Bosch pre-cat lambda model number with correct cable length that is suitable for a BES-engined 2.7T A6 would be much appreciated - I think I need to get these sooner rather than later.

Many thanks all.

[cidrox50]

OE part number is 1K0998262Q,for which Bosch part number is 0 258 010 032,or,more conveniently,16132.The 16132 is an updated version of the 16109,which was the original
fitment,now discontinued.Should fit out of the box.

[Guest 2]

Go you your local dealer and they can get you the part number via your VIN to ensure the correct version listed for your chassis.