W209 CLK 200 Check Engine Light Issue

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New Member
May 17, 2023
Hello, i’ve been watching over these forums for a while and would like to thank you for the tremendous amount of help so far.

I have bought a CLK200 September 2003 M271 and the car is great! Silver with blue leather! Love the car.

So moving along, I have had a continuous fault with check engine light, current milage is 117,000.
The car is using so much fuel and i can smell and see exhaust fumes when accelerating/ startup. Approx 18mpg mixed.

I have so far, changed O2 sensor just past engine to exhaust, cam sensors, wiring extension for cam sensors, new thermostat, opened the wires and cleaned the small amount of oil residue from ecu connector and o2 sensors, new air filter and hose intake, cleaned maf, oil service done and, oil looks good on cap no water. New spark plugs, vac test done at garage with no leaks. not to sure what to do next in order to get this check engine light to go off and get the car running not so rich on fuel?

Car drives good no juttering or rough idle, sits pretty at 600/700. And drives fine. I hope someone can point me in the right direction to help get this resolved as i plan on taking this car to 200k miles!

Vacum hose?
Oil in loom?
Pipe under air box?
PCV valve?
Throttle body?
Non return valve at intake manifold clogged?

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P2029 mixture format self adaptation (fuel trim)

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