M-Class (W163) Produced 1998-2005: ML 230, ML 320, ML 350, ML 400 CDI, ML 430, ML 500, ML 270 CDI

CE code PO173

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Old 05-13-2006, 02:57 PM
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ML 430
CE code PO173

ok got a check engine light and pulled a PO173 Fuel trim malfunction bank 2?? anybody help me out with this??? thanks MC
Old 05-13-2006, 04:17 PM
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2014 RX 350 F Sport, 2007 Scion tC, 2000 ML 430 Money Pit Finally Gone! Oh Happy Day!
Originally Posted by imwalkin
ok got a check engine light and pulled a PO173 Fuel trim malfunction bank 2?? anybody help me out with this??? thanks MC
According to Wolfgangs website http://www.whnet.com/4x4/dtc.html

P0170 Fuel Trim Malfunction (Bank 1) ) check vaccum leaks first or
P0171 System too Lean (Bank 1) ) faulty MAF (mass air flow) sensor
P0172 System too Rich (Bank 1) )
P0173 Fuel Trim Malfunction (Bank 2) )
P0174 System too Lean (Bank 2) )
P0175 System too Rich (Bank 2) )

Check for vaccum leaks first or faulty MAF (mass air flow) sensor
Old 05-13-2006, 08:40 PM
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98 ML320
My check engine light been on since last summer. I had the same code as yours. Mines also had P0171 for the MAF. So what does the P0173 mean? How do you check for vacuum leaks? I also read that cleaning the MAF will help. What is i do clean it. will i need to reset the engine light? or the light will go off by itself knowing the cleaner has done its job?
Old 05-14-2006, 08:35 AM
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use a precision electronis cleaner for the maf....dont touch anything inside!! and for the vac leak i may just spray al little WD around and listen for the idle to raise up...hopefully leading me to the leak!!! I'll let you know!!! mc
Old 05-14-2006, 09:20 AM
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1967 Morris Cooper "S", 1983 911SC, 1997 Toyota Tacoma, 1999 HD FXSTB, 1998 C43
Exclamation Don't Waste Your Time - Replace It

You can clean the MAF it'll come back (CEL)....replace the MAF, they're about $200 on the bay shipped. They're $264 through www.autohausaz.com - shipped. Don't waste your time at the dealer, it's a ten minute job to replace. The MAF IS a common problem on MB's.

You can reset the CEL by either correcting the problem or disconnecting the battery; however, if the problem persists, the CEL will reilluminate.

Last edited by StapleGun; 05-14-2006 at 09:22 AM.
Old 05-16-2006, 06:33 AM
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well as you stated its a ten min job...even quicker just to try cleaning it.... its looked pretty dirty...so I soaked it, let it dry, and put it back..... time will tell.....it was worth a shot...
Old 05-22-2006, 06:16 AM
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so I wasted my time and cleaned my maf and it looks like I maybe in the clear.....the ce light went out on its own, and it been a few days..... I still think I will pick a new one up...but now have the luxury of shopping around for a better price.... anyone find anything good????
Old 05-22-2006, 07:36 AM
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2014 RX 350 F Sport, 2007 Scion tC, 2000 ML 430 Money Pit Finally Gone! Oh Happy Day!
Originally Posted by imwalkin
so I wasted my time and cleaned my maf and it looks like I maybe in the clear.....the ce light went out on its own, and it been a few days..... I still think I will pick a new one up...but now have the luxury of shopping around for a better price.... anyone find anything good????
Best price I've seen lately has been @ http://www.autohausaz.com/search/pro...0Mass%20Sensor, $230.24 with free shipping
Old 05-22-2006, 12:52 PM
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Originally Posted by imwalkin
so I wasted my time and cleaned my maf and it looks like I maybe in the clear.....the ce light went out on its own, and it been a few days..... I still think I will pick a new one up...but now have the luxury of shopping around for a better price.... anyone find anything good????
you have the directions on cleaning it?
Old 06-23-2006, 01:19 AM
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Question MAF Spec?

I got codes p0170 & p0173 on my ML430, cleaned the MAF, light went off. But, the LTFTs are both still high (+24.2%/+25%) and STFTs are 0-2% at idle, so it won't be long before the DTCs are triggered again.

I ran a test with an OBD2 logger and the MAF reads 0.502 lb/min (3.8 g/s) at idle, up to over 15 lb/min (114 g/s) at WOT, 5300 RPM. These numbers seem plenty high compared those for other vehicles I've seen, anybody know if they're reasonable for my vehicle? I just don't want to replace the MAF and find out it was something else.

STFTs are all over the place under varying loads but are at least as positive under load as at idle, making an air leak unlikely. Thanks for any thoughts.
Old 01-19-2007, 10:39 PM
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W163 & 203
Hello guys
I have mine check engine on out of the blue and I checked is Fuel Trimming Bank 1 & 2 and I found out is AMS...is there anyone know how to clean it before I replace it or if anyone know the correct instruction to clean it
Thank s for your help and time.....
Old 01-20-2007, 11:38 AM
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2000 ml320 1986 560sel 1973 280se4.5
Just checked Autohausaz. $200 (today,at least).
Old 01-20-2007, 01:15 PM
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No light but the error P0173-133

I don't have any check engine light on but while checking a full test with star diagnostic system at dealer we got the P0173-133 code
"Selfadapation of mixture formation ... at limit value"!

Question: Is the light broken? then why I don't have other alarm about that?
I order to duble check I put key in position 2 (engine stop) were most of the sytem lights like SRS, ESP,ABS, service brake are on but the engine light not!

It's an S320 MY2000.
Old 01-22-2007, 09:30 AM
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W163 & 203
Morning guys....
I have a thought that would it probably the check engine is on simply cz I forgot to clean up and wash my air filter...I had replace it 10K earlier and I used K & N and after I clean up and washed it last night and it seems like everything now back to normal...I havent open and clean up the MAF cz I figure if the MAF that broke then check engine will come out again...
I ll keep it post it....after few days try...thanks.....
Old 01-23-2007, 06:14 PM
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Originally Posted by Pottie
Morning guys....
I have a thought that would it probably the check engine is on simply cz I forgot to clean up and wash my air filter...I had replace it 10K earlier and I used K & N and after I clean up and washed it last night and it seems like everything now back to normal...I havent open and clean up the MAF cz I figure if the MAF that broke then check engine will come out again...
I ll keep it post it....after few days try...thanks.....
was curious about the same thing.. Please keep us posted. My car won't pass smog until I get that CEL off.
Old 01-24-2007, 05:21 PM
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Hello so far I ve been driving about 60 miles since I clean up the air filter and so far the check engine is off...
There is another way if just in case is pop again then I ll clean up my MAF using the MAF cleaner that you could get it in pepboys....
If that one still not working then I ll go ahead replace it...
I still believe is worth to check n clean the air filter n MAF before u replace it

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