P0171/P0174 - hope this helps someone else ML500
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Joined: Aug 2018
Posts: 132
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From: Lawrence, KS
2003 MB C240. 2004 ML500, 2005 F150
P0171/P0174 - hope this helps someone else ML500
I replaced my valve cover gaskets a few months ago on my ML500 and it solved the oily mess under my hood. Fast forward to yesterday, my wife is driving the vehicle, and the CEL/MIL comes on. She said its not doing anything weird, so I told her to drive it home after her appointment and i'd scan it when i got home. A few hours later I go out after work and scan it. P0171 and P0174, banks 1 and 2 lean. hmm..
I start taking the intake off and what I thought would be the culprit, wasn't. I figured the accordian tube had cracked, but nope, it looked good. I took the engine cover off and started poking around when I found it. The cheap amazon.com hose kit I bought had a failed part. The valve cover hose that goes to the back of the engine on the driver's side developed a 1.5 inch long crack along the seam and was sucking air. I replaced that hose with a generic piece of thick vacuum hose I had lying around, and the seller on Amazon.com is sending me another hose/kit to replace the broken piece. Glad it was an easy fix, but I think I'm also going to invest in a genuine mercedes hose kit for this car since the other side will probably fail as well. Aside from that, I hit 64k miles on my 04 ML500 the other day and aside from a leaking windshield washer reservoir and defrost actuator (AC blows through the defrost section even when set to vent), the car has been pretty flawless. I guess it could be just a broken actuator arm, but I haven't opened up the driver's underside dash to look at it yet.
I start taking the intake off and what I thought would be the culprit, wasn't. I figured the accordian tube had cracked, but nope, it looked good. I took the engine cover off and started poking around when I found it. The cheap amazon.com hose kit I bought had a failed part. The valve cover hose that goes to the back of the engine on the driver's side developed a 1.5 inch long crack along the seam and was sucking air. I replaced that hose with a generic piece of thick vacuum hose I had lying around, and the seller on Amazon.com is sending me another hose/kit to replace the broken piece. Glad it was an easy fix, but I think I'm also going to invest in a genuine mercedes hose kit for this car since the other side will probably fail as well. Aside from that, I hit 64k miles on my 04 ML500 the other day and aside from a leaking windshield washer reservoir and defrost actuator (AC blows through the defrost section even when set to vent), the car has been pretty flawless. I guess it could be just a broken actuator arm, but I haven't opened up the driver's underside dash to look at it yet.
