2001 CLK230K emissions failure help required

[gafrwi]

Hi all, please could someone help me.
I have a 2001 CLK 230K M and today it failed its MOT test on emissions.
The readings are as follows

Fast Idle Test:

Min Limit Max Limit Actual Value Pass/Fail
RPM 2150 2850 2221 Pass
CO ------ 0.300 6.089 Fail
HC ------ 200 188 Pass
Lambda 0.970 1.030 0.832 Fail


Second Fast Idle Test:

Min Limit Max Limit Actual Value Pass/Fail
RPM 2150 2850 2312 Pass
CO ------ 0.300 7.302 Fail
HC ------ 200 259 Fail
Lambda 0.970 1.030 0.796 Fail

Natural Idle Test:

Min Limit Max Limit Actual Value Pass/Fail
RPM 650 850 752 Pass
CO ------ 0.500 9.610 Fail

Overall Result: Fail

Could someone please tell me what I need to replace to get the emissions back into check.
The car has covered 112000 miles

 

[television]

Hello and welcome,, wait till SAM or a techie comes on line, it may just need what we call the Italian tune up

 

[Ellsy Tanners]

Hi gafrwi,

How long have you had the car?
Sounds to me as if someone has de-catted it or there is something eles badly wrong.
A 02 sensor problem. has it had any work for the oil in the engine wiring loom problem etc?

 

[MB TECH WARRINGTON]

the first thing you need to try is a good quality injector cleaner, cleans from tank to exhaust, then give the car a good thrashing on the way to the mot station,
im not judging how you drive, but if you just potter about, short journies, it can cause these issues to arise.

if this does not work, then testing on star machine will be needed to see whether cat is insufficient etc, anything from airmass to dodgy cat can cause this.

 

[Autofix]

With CO of between 7 and 9 percent there is an actual fault.
I wouldn’t image an Italian tune up or a mechanic in a tin would cure this so I think the best bet would be to get it looked at, as MB Tech says above.

 

[Uncle Benz]

I agree with Autofix here. This level of CO is due to a serious fault. Could be something like a coolant temp sensor. Decent indie with code reader and live data stream is your next step.

CO is partially burnt fuel - the readings are way too high

HC is unburnt fuel, and these readings are not way off the scale, so you can eliminate plugs/leads to a reasonable extent.

Edit to add- 2001 probably got coil packs instead of leads, but you get my drift...