MOT failed on emissions

[iD]

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Hi
Just went to do the MOT yesterday and failed on idle emission. Any idea what to look for or what to do next?
The guy at the MOT centre told me that it's the cat converter but another garage told me that I should start by replacing Lambda sensor. I wanna know what your say is on that. (Thanks in advance)

The results are as blow

Fast Idle Test
RPM=
2693 Max Limit=2850 (Pass)
CO=0.600 Max Limit=0.300 (Fail)
HC=122 Max Limit=200 (Pass)
Lambda=1.060 Max Limit=1.030 (Fail)

Second Fast Idle test
RPM=
2722 Max Limit=2850 (Pass)
CO=0.592 Max limit=0.300 (Fail)
HC=120 Max Limit=200 (Pass)
Lambda=1.038 Max Limit=1.030 (Fail)

Natural Idle Test
RPM=
767 Max Limit=900 (Pass)
CO=0.499 Max Limit=0.500 (Pass)

The Car is 1996 W202 C180
 

television

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I think that all you need to do is an Italian tune up,, take the car for a high speed run with the box locked in 2 or 3 and get it really hot,,then test again while still hot
 
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[iD]

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thanks for your input
I got it checked with kwikfit and the exhaust was blowing from 3 different places so they sealed it..cost me £75 :S
i know it's kwikfit for you
do you recon any fuel additive to use as well?
gonna take it down for retest tomorrow
 

Mark A

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If you are taking it down for retest today, I wouldn't put any additives in. It's best to put them through the system and let them do their thing for a full tank.

I have previously used CataClean. Seemed to to the trick on my old Subaru.
 

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Take it for a fast drive , and when hot lock the car into second and give a good fast run,just before you take it in.

Do not add anything at this stage as said above
 

Alex Crow

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definitely go for the hot drive as your main problem is high co, suggesting the cat is not working well - it may recover with a good heat cycle and blow out (italian tune up). your other fail of high lambda values can easily be caused by holes in the exhaust, these have been fixed.
 

owenrich

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slk
definitely go for the hot drive as your main problem is high co, suggesting the cat is not working well - it may recover with a good heat cycle and blow out (italian tune up). your other fail of high lambda values can easily be caused by holes in the exhaust, these have been fixed.

I have a similar problem i.e. MOT emissions failure. CO figures are way too high at 7.27%, 7.20% & 8.96% over the three tests! HC readings are 207ppm & 222ppm just above the max of 200ppm. Lambda was 0.80 which was under the 0.97-1.03 limit. Any suggestions please?
 

Alex Crow

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high co, reasonable hc (will be high with the co that high), lambda very low. and your car is an slk200k? this all points to a failed lambda sensor, but i would expect your engine warning light to be lit on the dash.

the test values tell you that the vehicle is running very rich, with low oxygen content (if you had high co but with correct lambda this would point to a cat failure). are we assuming the correct vehicle? if so IS the engine warning light on??
 

owenrich

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Your Mercedes
slk
high co, reasonable hc (will be high with the co that high), lambda very low. and your car is an slk200k? this all points to a failed lambda sensor, but i would expect your engine warning light to be lit on the dash.

the test values tell you that the vehicle is running very rich, with low oxygen content (if you had high co but with correct lambda this would point to a cat failure). are we assuming the correct vehicle? if so IS the engine warning light on??

Hi again and thanks for your help again. The engine management light is on with codes P0130 & P0131. I have fitted a new front O2 sensor (Fuel Parts direct OE type), the code had been P0135, but changed after fitting. You will see from my other answer that I have been working to get this right pre MOT. The car is a 2003 SLK200K with the M111-958 engine. Car starting & running well, but using fuel (21mph). I think my next move is the MAF, but little sign of oil contamination here. Your advice most welcome. Thanks.
 

owenrich

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Your Mercedes
slk
SLK emission failure, thanks for all the help so far.
 

owenrich

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Your Mercedes
slk
high co, reasonable hc (will be high with the co that high), lambda very low. and your car is an slk200k? this all points to a failed lambda sensor, but i would expect your engine warning light to be lit on the dash.

the test values tell you that the vehicle is running very rich, with low oxygen content (if you had high co but with correct lambda this would point to a cat failure). are we assuming the correct vehicle? if so IS the engine warning light on??

Hi, the engine management light is on with codes P0130 & P0131. The car is the 2003 SLK200K chassis170444 & engine 111958.
 

owenrich

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Your Mercedes
slk

Alex Crow

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W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
i see a couple of p0130 definitions, open circuit or implausible value during decel shut off (when coasting). i still suspect the sensor...
 


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