R129 SL500 Emissions fail - o2 sensor...?

[sprankine]

Hi all,
My 1994 SL500 is running too much CO to pass the MOT emissions (first time it has failed.)
My specialist (SS motors, Weybridge) thinks its very unlikely to be Cats, so conclude that a new O2 sensor should resolve the issue.
Anyone else out there had a similar issue?
The car only has 64k miles and is running perfectly with no codes.
Cheers

[jimdollar]

Did they give you a printout with the readings? Normally if the cats are faulty(and everything else is ok) you get a reading of up to 0.5% CO maybe a little more but if its much more than that it won't be the Cats.

Edited by jimdollar on Friday 19th July 11:34

[Hoolio]

Hoping someone can help, please. My 96 SL500 failed its MOT today on emissions. What should I be looking at to rectify please? I should also point out that the garage had to add fuel cleaner to get the emissions down to this, was much higher before.

Engine Oil Temp - Actual 94
Fast Idle Test 1
CO - Actual 0.7%
HC - Actual 60ppm
Lambda - Actual 1.02

Fast Idle Test 2
CO - Actual 0.6%
HC - Actual 67ppm
Lambda - 1.01

Natural Idle Test
CO - Actual 0.3%

Thanks in advance.

[ras62]

Could be a number of things. Check the fault codes. Possible one cylinder isn't sparking or a stuck injector. Both hard to notice on an 8cylinder