Hi everyone, looking for some advice with my 2005 clk200.

EML came on 6 months ago and threw up P0171 fault code, engine too lean. After taking it to a specialist who couldn’t diagnose the cause, even with the STAR diagnostics, I started to investigate myself to save some money.

First issue I found was oil in the cam magnets. I’ve changed both of those for new items and added the extra wiring in aswell, not cheap! I think I managed to catch it in time as there was very little oil in the ECU plugs and none in the MAF plug.

Changing the magnets did not fix the issue and I then found that the hose under the air box was split, changed this for the updated part, but I still have the EML.

I the ran the car for a few days with the MAF unplugged, this gave me the running rich fault which lead me to believe it was at fault. However I have swapped this today and the EML came back on after 10 miles or so.

I’m totally pulling my hair out now! The only things left to change are the lambda sensors, are these worth doing? Are there any other common air leaks? When fitting the replacement hose under the air box, I noticed it didn’t have a clip on the end with the least access, the hose itself is very very tight, is this likely to cause a leak which could affect fueling or is it normal?

Thanks guys, sorry for the long post but I’ve tried a lot of things already!