SL/R129: Need some details on MAF Housing Replacement
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 21
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From: Seattle
2001 SL500 F1 Edition
Need some details on MAF Housing Replacement
Hi Guys,
Need some DIY info on the MAF replacement. Read the one on the W210 forum but ours on the SL500 is in a different location and seems to be attached in a different fashion.
For some reason SEARCH is not returning anything.
2001 SL500
63xxx miles
Check Engine Light on with Codes 0171 and 0173
Removed just the hot wire from housing
Cleaned the hot wire with CRC MAF cleaner
CEL still on and ordered new MAF from AutohausAZ
So...I cannot see how the housing comes off...anybody?
Thanks!
Need some DIY info on the MAF replacement. Read the one on the W210 forum but ours on the SL500 is in a different location and seems to be attached in a different fashion.
For some reason SEARCH is not returning anything.
2001 SL500
63xxx miles
Check Engine Light on with Codes 0171 and 0173
Removed just the hot wire from housing
Cleaned the hot wire with CRC MAF cleaner
CEL still on and ordered new MAF from AutohausAZ
So...I cannot see how the housing comes off...anybody?
Thanks!
MBWorld Fanatic!
Joined: Nov 2007
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From: Daytona, Florida
SL600
It's an effin' PITA, unless you have very small hands.
First, remove the entire air cleaner assembly, and put it aside. The circular black thing with the grate underneath where the airbox assembly sits is the MAF.
It's secured with a couple of metal ribbon clamps, the first of which is easy to get to, but the second one is waaaaaaaaaaaaaay down at the bottom buried in between the intake manifold. You will need a flexible screwdriver to be able to get down there to the clamp and loosen it.
After you have loosened the clamp, unhook the twist-plug connection, and then the MAF just pulls straight up and out, and the new one slides into its place. Then, just do the opposite of the above to put it back together.
First, remove the entire air cleaner assembly, and put it aside. The circular black thing with the grate underneath where the airbox assembly sits is the MAF.
It's secured with a couple of metal ribbon clamps, the first of which is easy to get to, but the second one is waaaaaaaaaaaaaay down at the bottom buried in between the intake manifold. You will need a flexible screwdriver to be able to get down there to the clamp and loosen it.
After you have loosened the clamp, unhook the twist-plug connection, and then the MAF just pulls straight up and out, and the new one slides into its place. Then, just do the opposite of the above to put it back together.
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From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
MAF throwing those codes is a common failure - most often after a service/air filter change. Be sure you also replace to the two rubber O-rings on the top and bottom of the MAF housing - about $6 at the dealer. The heat dries them out so they don't seal like they should as they age. BTW, Bosch make the exact same MAF, with the same part number minus the three point star logo and minus some of the additional mark-up.
- FD
- FD
Last edited by Floobydust; Jan 19, 2009 at 10:17 PM. Reason: fixed typo
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 21
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From: Seattle
2001 SL500 F1 Edition
So here is another question, I removed the actual MAF (the 4 inch long piece that is positioned into the airflow that the wires plug into) out of the round housing to try the cleaning method (didn't work...).
Could I simply remove and replace the actual MAF instead of the whole round plastic body?
Thanks!
Could I simply remove and replace the actual MAF instead of the whole round plastic body?
Thanks!
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
Likes: 133
From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
So here is another question, I removed the actual MAF (the 4 inch long piece that is positioned into the airflow that the wires plug into) out of the round housing to try the cleaning method (didn't work...).
Could I simply remove and replace the actual MAF instead of the whole round plastic body?
Thanks!
Could I simply remove and replace the actual MAF instead of the whole round plastic body?
Thanks!
I wouldn't recommend it. The MAF measures the air density by measuring the heat transfer across a tiny gap at a given temperature. The spacing/dimensions are critical so I wouldn't risk it. It's so easy to just replace the whole thing (and you have to take the housing off to replace the E-rings anyway) it's not worth the risk. Be sure you get an OBDII reader and reset the codes after you replace the MAF. Good luck.
- FD
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 21
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From: Seattle
2001 SL500 F1 Edition
Ok, Thanks! I'll RnR the whole thing.
I found this:
http://www.panchogun.com/FVWebPhotos...-MAF-5x100.jpg
This looks the same as the 2001 MAF install.
Cheers!
I found this:
http://www.panchogun.com/FVWebPhotos...-MAF-5x100.jpg
This looks the same as the 2001 MAF install.
Cheers!
Last edited by Bruce SEA 993; Jan 21, 2009 at 09:27 PM.
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MBWorld Fanatic!
Joined: Nov 2007
Posts: 1,517
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From: Daytona, Florida
SL600
Ok, Thanks! I'll RnR the whole thing.
I found this:
http://www.panchogun.com/FVWebPhotos...-MAF-5x100.jpg
This looks the same as the 2001 MAF install.
Cheers!
I found this:
http://www.panchogun.com/FVWebPhotos...-MAF-5x100.jpg
This looks the same as the 2001 MAF install.
Cheers!
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MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
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From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
No, that 2001 install looks soooooooooo much easier. It looks like they fixed what I was griping about, and used a bracket that you can easily release with a flathead instead of a ribbon clamp that you need special tools to get to and will scrape your knuckles trying to loosen.
- FD
MBWorld Fanatic!
Joined: Nov 2007
Posts: 1,517
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From: Daytona, Florida
SL600
My 2000 has the quick release clamps just like the ones shown in the Bruce's post (http://www.panchogun.com/FVWebPhotos...-MAF-5x100.jpg). A quick flick and they're off/on.
- FD
- FD
I wonder what year they switched over to the quick-release bracket?
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 21
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From: Seattle
2001 SL500 F1 Edition
Thanks all for the replies...it is exacly as Pancho describes in his website. It took all of 5 minutes...seriously!
So now, I drove the car and the CEL is still on. I think I have to go through 3 "cycles" or so before it will clear. So what is a cycle? Me thinks it is a drive then cool down and then a cold start.
Thanks!
So now, I drove the car and the CEL is still on. I think I have to go through 3 "cycles" or so before it will clear. So what is a cycle? Me thinks it is a drive then cool down and then a cold start.
Thanks!
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
Likes: 133
From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
- FD
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 21
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From: Seattle
2001 SL500 F1 Edition
Thanks FD,
The CEL has not cleared so I better go find a place that can reset the OBDII.
I had Autozone read them but they "cannot reset" according to the kid there.
I will check wit the guys on the Rennlist 993 forum to see if one of the local guys has a reader.
Cheers!
The CEL has not cleared so I better go find a place that can reset the OBDII.
I had Autozone read them but they "cannot reset" according to the kid there.
I will check wit the guys on the Rennlist 993 forum to see if one of the local guys has a reader.
Cheers!
Junior Member
Joined: Nov 2007
Posts: 18
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'02 SL500
Allow me to chime in regarding my own CEL situation.....
My CEL started coming on and off until it decided to stay on. First of all I replaced the fuel cap (lowest cost attempt) but the CEL did not clear itself.
Then I followed advice given here and was able to clean the AMS on my '02 SL500 with no problem. However, the CEL stays lit after a week's-worth-of-cycles.
So, does that inidcate that I ought to replace the AMS
OR
should I pursue finding someone that will clear the code for me first and wait if it comes back on?
My CEL started coming on and off until it decided to stay on. First of all I replaced the fuel cap (lowest cost attempt) but the CEL did not clear itself.
Then I followed advice given here and was able to clean the AMS on my '02 SL500 with no problem. However, the CEL stays lit after a week's-worth-of-cycles.
So, does that inidcate that I ought to replace the AMS
OR
should I pursue finding someone that will clear the code for me first and wait if it comes back on?
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
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From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
kunzet -
An intermittent CEL followed by hard failure can be from a myriad of sources, so the MAF isn't necessarily the issue automatically. You should get someone to read the OBDII code(s) then replace/repair per the code (mixture [which would indicate MAF failure], O2 sensor, vapor recovery, etc.). After you effect repairs/replacement, have the CEL reset and "drive" it for a while to force the OBDII diags to run. OBDII is a very useful system that can point you right to a problem with little or no guesswork. Use it to your advantage.
- FD
An intermittent CEL followed by hard failure can be from a myriad of sources, so the MAF isn't necessarily the issue automatically. You should get someone to read the OBDII code(s) then replace/repair per the code (mixture [which would indicate MAF failure], O2 sensor, vapor recovery, etc.). After you effect repairs/replacement, have the CEL reset and "drive" it for a while to force the OBDII diags to run. OBDII is a very useful system that can point you right to a problem with little or no guesswork. Use it to your advantage.
- FD
Last edited by Floobydust; May 20, 2010 at 11:02 PM. Reason: Added salutation
Junior Member
Joined: Nov 2007
Posts: 18
Likes: 1
'02 SL500
I finally got a reading off the OBDII and the codes are:
P0170 Fuel Trim
P0173 Fuel Trim
Does that point to a defective MAF?
Alright, I did a search on the forum outside of the R129 thread and found the sticky post that lists all of the error codes.
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) )
Initially the CEL came on on occassion during the 2nd half of '09 and that's when I replaced the gas cap. However, after a short while the light came back on and stayed on. Are there other places to check when troubleshooting a 'vacuum leak'?
I also found another post that talked about the MAF being the culprit even though I don't show a P0171 code.
P0170 Fuel Trim
P0173 Fuel Trim
Does that point to a defective MAF?
Alright, I did a search on the forum outside of the R129 thread and found the sticky post that lists all of the error codes.
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) )
Initially the CEL came on on occassion during the 2nd half of '09 and that's when I replaced the gas cap. However, after a short while the light came back on and stayed on. Are there other places to check when troubleshooting a 'vacuum leak'?
I also found another post that talked about the MAF being the culprit even though I don't show a P0171 code.
Last edited by kunzet; Jun 15, 2010 at 08:26 PM.
Newbie
Joined: Apr 2008
Posts: 10
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1998 SL500
Does the car run bad or die at idle? As the MAS goes bad the engine performance will deteriorate. My experience is with a M119 so yours may be a little different but the car will get to the point where it will not run well at any speed. On an M119 you must unplug the MAS to get the car to run on the default map which is supposed to happen when the MAS fails but doesn't - not sure if the same is true on an M113 but its worth a shot. The engine will run fine with the MAS unplugged to verify the diagnosis.
If the car isn't running bad and you are only getting fuel trim codes, start with a tune up if it is due and go from there. At least check the plugs, air filters, and all the vacuum hoses under the hood and engine cover. Reset the CEL and check for codes again if it lights. Fuel trim codes could be caused by lots of things but I'd be more suspicious of O2 sensors or the catalytic converter if the car is not running badly. Whatever the problem is, trust me, it will eventually make itself known.
If the car isn't running bad and you are only getting fuel trim codes, start with a tune up if it is due and go from there. At least check the plugs, air filters, and all the vacuum hoses under the hood and engine cover. Reset the CEL and check for codes again if it lights. Fuel trim codes could be caused by lots of things but I'd be more suspicious of O2 sensors or the catalytic converter if the car is not running badly. Whatever the problem is, trust me, it will eventually make itself known.
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
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From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
Junior Member
Joined: Nov 2007
Posts: 18
Likes: 1
'02 SL500
FD.....you win.
I ordered a replacement MAF sensor installed it a couple of nights ago and after about a dozen re-starts the CEL cleared.
She drives much better with the combination of new spark plugs (after 58k miles) and the new MAF unit.
All is good! and thanks to everyone here.
I ordered a replacement MAF sensor installed it a couple of nights ago and after about a dozen re-starts the CEL cleared.
She drives much better with the combination of new spark plugs (after 58k miles) and the new MAF unit.
All is good! and thanks to everyone here.
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 21
Likes: 0
From: Seattle
2001 SL500 F1 Edition
Glad you are up and running!
I looked at the dates and I did mine 18 months ago and is still running strong.
Just took the top off today as July 5th is the real start of summer for us in Seattle.
Cheers!
I looked at the dates and I did mine 18 months ago and is still running strong.
Just took the top off today as July 5th is the real start of summer for us in Seattle.
Cheers!
Newbie
Joined: Jul 2012
Posts: 5
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'01 SL 500 (R129) '10 Audi S5
Way after the fact.....
Its 2013 and this thread just saved my CEL code I have been dealing with in my '01. Just wanted to say thanks to the thread and hope I can contribute one of these days!
