Originally Posted by carlito
I just cleaned the MAF sensor in my 04 1.4t today. Before today, all 4 cylinders were misfiring. After cleaning, CEL went away and it was no longer idling rough on a cold start but I'm still getting one fault code. And CEL came back later in the day.
17519 - Oxygen (Lambda) Sensor Regulation: Bank 1
P1111 - 002 - System too Lean
This is the only engine fault code I'm getting now. The car idled fine when I disconnected the wire to the MAF so does that mean it's okay or needs to be replaced?
I have never cleaned a MAF and had any sucsess unless it was clearly contaminated from like an over oiled K&N filter. What really happened is the engine management has richened it up to compensate for the lean condition masking the issue. But it reaches a point where it turns the light on for the lean code if it adds enough extra fuel. You have an air leak, like breather parts under the intake manifold or behind the valve cover. Or the pcv valve has failed, or some other torn or cracked hose after the MAF sensor.