P0171 Mercedes-Benz -

Question

The car shows the code P0171 and P0301 to P0304 and additionally turn the engine failure warning. The car shakes at idle but it works well when running without apparent loss of power. I changed the spark plugs, air filter and the MAF sensor but still the same. What could be the problem?
Thank you

Answer 1

P0301 Misfire number 1 cylinder

P0304 Misfire number 4 cylinder

P0171 Fuel trim Lean Bank 1

You still have a misfire condition , the fuel injector would be the next step in determining the misfire condition., but it would also be better to rule out a mechanical condition with the suspected cylinder causing a misfire condition such as a leak down test or compression test