P0171 & P0174 Error - Fixed MAF, Didn't Help
Thread Starter
Newbie
Joined: Aug 2018
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2009 ML350
P0171 & P0174 Error - Fixed MAF, Didn't Help
I've been getting constant P0171 & P0174 error codes. - It only happens when I run the AC for a while.
Reading other cases I've gone ahead and replaced my MAF with a new OEM Bosch MAF. This didn't help as the CEL and error codes returned a few hours after turning on the AC.
Any suggestions on where/what I should check next?
Thinking of smoking the car and seeing if there are any vacuum leaks.
Reading other cases I've gone ahead and replaced my MAF with a new OEM Bosch MAF. This didn't help as the CEL and error codes returned a few hours after turning on the AC.
Any suggestions on where/what I should check next?
Thinking of smoking the car and seeing if there are any vacuum leaks.
MBWorld Fanatic!
Joined: Oct 2011
Posts: 7,107
Likes: 765
From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Chris, why you changed the MAF Sensor, I do not know. MAF generates its own code P0101, which you did not report.
Possible cause of codes is the air duct hose (#11) inPDF. And yes, have it smoked
Possible cause of codes is the air duct hose (#11) inPDF. And yes, have it smoked
MBWorld Fanatic!
Joined: Oct 2011
Posts: 7,107
Likes: 765
From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Chris, every component has its own code assigned to it. Don't start replacing things because you think it could be faulty.
Look at the description of the codes, then look at the explanation and possibilities of the codes. What is at the top of the list of possibilities?
Thread Starter
Newbie
Joined: Aug 2018
Posts: 5
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2009 ML350
Thanks for the help so far. - If I'm reading this correctly (which I'm new to all of this so bear with me) my issue is "unmetered air" - if that's the case how do I diagnose the problem? My ODB 2 meter is only giving me the P0172 and P0174 error codes - Or is this suggestion that my issue is with the main control unit itself?
MBWorld Fanatic!
Joined: Oct 2011
Posts: 7,107
Likes: 765
From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
I see that you posted on two different forums with the same problem and you replaced parts without having the codes to support those replacements. If there was a component failure, there would be a code for that component and the two codes you already have.
Whenever the codes are on both banks, 90% of the time it is a vacuum leak.
When you had the truck smoked, were you there watching? Was it done with a professional smoke machine? How much did they charge you?
