Engine air filters replaced = lean mixture faults
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Joined: Dec 2025
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2010 C300 Sport
Engine air filters replaced = lean mixture faults
Had A service done at 150k and both engine air filters were replaced. A few days later check engine light is on with fault codes 0739, 0946, 2095, 0745, 2091 regarding lean mixtures cylinders 1 and 2, inefficient catalytic converter cylinder 2, plus 0954 shutoff valve charcoal canister stuck closed. Could this be due to air filters being replaced? Improperly sealed?? Any ideas? Car seemed to be running great before service.
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Joined: Jan 2024
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From: Los Angeles, CA
2010 C300 Sport
Shop said they did a smoke test and did not find any leakage. They suggested a new gas cap because the O-ring on mine was showing signs of wear. Replaced cap and deleted all the fault codes. Drove it for four days without incident then today on the way to work I hit a bump and the CE light came on. Not sure if that was a coincidence. I have noticed a recurring fault code 0946: the efficiency of the catalytic converter (cylinder bank 2) is insufficient.All the codes listed above were marked "current" when I scanned, but 0946 was marked "current and stored." Returning to shop tomorrow.
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2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
Two things to check for possible problems:
1-Carefully examine the vapor canister for a hairline crack near the mounting points.
2-Downstream oxygen sensor. Also examine the entire exhaust system for corrosion and leaks at the connections.
No. 1 drove us crazy on a 2010 BMW. Hitting the bump is the common fact.
1-Carefully examine the vapor canister for a hairline crack near the mounting points.
2-Downstream oxygen sensor. Also examine the entire exhaust system for corrosion and leaks at the connections.
No. 1 drove us crazy on a 2010 BMW. Hitting the bump is the common fact.
