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Marty
Marty, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 53940
Experience:  Bosch Certified Master Technician with over 35 years experience in the automotive industry.
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I have just taken my Mercedes CLK for mot test and it failed

Customer Question

I have just taken my Mercedes CLK for mot test and it failed the emission test.
The garage then advised that the catalytic converter, the O2 center and the Lamdar centre(not sure of the correct spelling) needed to be replaced. Despite replacing all these part, it still failed a retest on emission. Now the garage has said they cannot figure out why.

Can anyone help explain what could be causing the emission failure.

Many thanks.
Submitted: 3 years ago.
Category: Mercedes
Expert:  Marty replied 3 years ago.

Marty :

Hi, my name is Marty. Is your check engine light on or had it been on previous to the repair work?

JACUSTOMER-wo9wrzvm- :

Yes it had been on prior to going in to the garage but that was because of transmission problem which i have had for a while due to leaks. I usually top up each time it goes into safe mode and that solves the problem until the oil level goes low again.

JACUSTOMER-wo9wrzvm- :

sorry hi i am peter

JACUSTOMER-wo9wrzvm- :

Hello! are you there.

Marty :

Sorry Peter I had to step away. Can you possibly post the fault codes that were stored in the engine control module?

JACUSTOMER-wo9wrzvm- : I have no engine code. The garage cannot provide any
JACUSTOMER-wo9wrzvm- : I mean fi have not been provided with a fault code
Marty :

Hi Peter, it will be impossible for me to advise you without the fault codes or the mot test results. Can you contact the shop and get the information?

JACUSTOMER-wo9wrzvm- :

The diagnostics did not return any fault code, but the car still failed on emission despite the garage replacing all the part I have earlier mentioned.This is why i came on your site to find out the possible reason(s) and solution. I was hoping this is a known problem with CLK and that a specialist mechanic would help provide a solution. I however would get the MOT test result tomorrow, and maybe it would provide some additional info.

Marty :

Hi Peter, if your check engine light is on there are definitely fault codes stored in the computer. If you can post the results of the MOT test I can advise you.

JACUSTOMER-wo9wrzvm- :

ok. I will provide that info by tomorrow.

Marty :

Sounds good, I'll wait to hear from you.

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