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-   -   P0171 & P0174 Error - Fixed MAF, Didn't Help (https://mbworld.org/forums/m-class-w164/717901-p0171-p0174-error-fixed-maf-didnt-help.html)

CreativelyChris Aug 10, 2018 07:24 PM

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.

Maj. Dundee Aug 10, 2018 09:20 PM

1 Attachment(s)
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

CreativelyChris Aug 16, 2018 06:06 PM

I had the car smoked and found no leaks.

My next guess is the MAP sensor or O2 Sensors? - Thoughts on which I should try first? Or anything else I should look at?

Maj. Dundee Aug 17, 2018 02:54 AM

1 Attachment(s)
https://cimg3.ibsrv.net/gimg/www.mbw...5096cfdb47.jpg
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?

CreativelyChris Aug 18, 2018 07:25 PM

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?

Maj. Dundee Aug 19, 2018 02:41 AM

https://cimg0.ibsrv.net/gimg/www.mbw...6e7c09b28b.jpg


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?


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