SLK/R170: Cleaning o2 and MAF sensors
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1967 Morris Cooper "S", 1983 911SC, 1997 Toyota Tacoma, 1999 HD FXSTB, 1998 C43
Chances are it's going to be under your air filter housing - here's a link for the cleaning of the MAF it's for a BMW, the MB MAF is identical though. MAF FILTER CLEANING LINK
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From: North Carolina
98 Black C43 , 12’ ML 350 Blutec
Originally Posted by StapleGun
Chances are it's going to be under your air filter housing - here's a link for the cleaning of the MAF it's for a BMW, the MB MAF is identical though. MAF FILTER CLEANING LINK
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SLK
Locations
The MAFS is located on the right side down low on the large black hose.
It has a large connector attached to it.
The O2 sensors, there are two they are located on the exhaust pipe before the cats.
The MAFS can be cleaned. You should go buy the 2001 MAFS connector pipe and relocate it to the upper position to eliminate the low end hesitation.
If the car has a rough idle at start up try using 89 octane gas it will fix the problem without any noticeable loss in performance. It will not hurt the engine to use 89 octane.
Want more power? Get Linh's pulley kit, it kicks *** and you will burn the rear tires right off in no time.
The link posted above is partially correct, it is not under the filter housing and it is correctly called a Mass Air Flow Sensor or MAFS for short.
It has a large connector attached to it.
The O2 sensors, there are two they are located on the exhaust pipe before the cats.
The MAFS can be cleaned. You should go buy the 2001 MAFS connector pipe and relocate it to the upper position to eliminate the low end hesitation.
If the car has a rough idle at start up try using 89 octane gas it will fix the problem without any noticeable loss in performance. It will not hurt the engine to use 89 octane.
Want more power? Get Linh's pulley kit, it kicks *** and you will burn the rear tires right off in no time.
The link posted above is partially correct, it is not under the filter housing and it is correctly called a Mass Air Flow Sensor or MAFS for short.
Last edited by Squishy; Jan 17, 2006 at 07:32 PM.
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Use Brake cleaner NOT carby cleaner.
Brake cleaner will drip dirt off and completely evaporate.
Some carby cleaners are too strong in the solvent side.
I just wipe a smear of engine oil on the o ring, on 1998 230slk it is in the ally bit where the MAF pushes in.
bazzle
Brake cleaner will drip dirt off and completely evaporate.
Some carby cleaners are too strong in the solvent side.
I just wipe a smear of engine oil on the o ring, on 1998 230slk it is in the ally bit where the MAF pushes in.
bazzle
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Just wanted to chime in about cleaning the MAF. I would not recommend using brake cleaner OR carb cleaner on the MAF. These chemicals are not deemed "plastic safe" and you could be corroding the plastic housing in addition to "cleaning" the hot wires, etc.
I used a product called "CRC Mass Air Flow Sensor Cleaner" which is supposed to be safe on all plastics and does an excellent job of cleaning the sensitive wires/plates on the MAF. It was about 6 bucks at the local auto parts store (Schuck's, in my case)
After cleaning, I noticed an immediate improvement. I bought my '99 E320 about 6 months ago and I thought it drove fine, because I had nothing to compare it to. My CEL came on with the code P0173 "Fuel Trim Malfunction - Bank 2" about a month ago and my idle felt a bit rough, so I decided to try and clean the MAF before spending the $$$ to replace it.
Wow! The acceleration is WAY better than it has ever been since I've owned the car! The idle is smooth as silk. 'Tis wild how such a tiny little wire makes such a huge difference.
Hope this helps somebody!
I used a product called "CRC Mass Air Flow Sensor Cleaner" which is supposed to be safe on all plastics and does an excellent job of cleaning the sensitive wires/plates on the MAF. It was about 6 bucks at the local auto parts store (Schuck's, in my case)
After cleaning, I noticed an immediate improvement. I bought my '99 E320 about 6 months ago and I thought it drove fine, because I had nothing to compare it to. My CEL came on with the code P0173 "Fuel Trim Malfunction - Bank 2" about a month ago and my idle felt a bit rough, so I decided to try and clean the MAF before spending the $$$ to replace it.
Wow! The acceleration is WAY better than it has ever been since I've owned the car! The idle is smooth as silk. 'Tis wild how such a tiny little wire makes such a huge difference.
Hope this helps somebody!
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CRC is a great company, I used to be a distributor for their products.Great to know.
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clear check engine ligh
Originally Posted by bazzle
There you go... a decicated cleaner. Do not wipe with a cotton tip as sensors have been reported damaged, spray only.
Brake clean has been used for years, carbi clean can damage plastic.
Bazzle
Brake clean has been used for years, carbi clean can damage plastic.
Bazzle
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From: Washington, DC
2002 SLK 32
Originally Posted by cesarmenjivar
...so after cleaning the sensor with the crc..how would i clear the code of the check engine light.. would i have to remove the battery? i heard that if you remove the battery you will need a code to start the car back on..is that true?
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From: Laguna Niguel, CA
Can you really clean an o2 sensor, one that's got caked on carbon buildup? Also, Squishy is wrong, all cars with cats have a pre and post cat sensor. When the code is for sensor 1, bank 1 it means pre-cat and drivers side (on V6 or V8), bank 2 is passenger side, sensor 2 is post-cat.
As for resetting codes, if you know the code then you probably have access to an obd2 scanner and that will reset codes. They are available pretty cheap these days, ebay or pep boys (had them for well under $100).
As for resetting codes, if you know the code then you probably have access to an obd2 scanner and that will reset codes. They are available pretty cheap these days, ebay or pep boys (had them for well under $100).
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From: Virginia and Texas
99 SLK 230 - US Model
MAF Cleaning
I have cleaned my MAF sensor on my 99 SLK on 2 occassions. My brother, who is a mechanic, recommends using "contact cleaner" electronic parts. Just spray it on and let it drip dry. It has worked great with no problems.
I would not recommend using vasoline as an o-ring lubricant, it will break down the rubber. I prefer a solicone based lubricant.
Good luck!!
I would not recommend using vasoline as an o-ring lubricant, it will break down the rubber. I prefer a solicone based lubricant.
Good luck!!
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From: New York
2001 E320
I took my car (2001 E320 57,400 miles) to dealer for CEL they told me I need Air Mass Flow Sensor replaced quoting a $750 bill. I declined to replace it after reading on in this messageboard. They charged me $109 for the diagonose.
I am planning on cleaning MAF this weekend with "CRC Air Mass Flow Sensor Cleaner", I also ordered a ODBII from www.autotap.com for $200 so I don't take my car to dealer again for small jobs like this. If cleaning does not work I will buy Mercedes brand MAF for $440 from the dealer and still save money.
I will take photos of this job and post them for next guy who wants do this yourself. Let me know if you guys suggestions e.g. if I need to change spark plugs etc.?
I am planning on cleaning MAF this weekend with "CRC Air Mass Flow Sensor Cleaner", I also ordered a ODBII from www.autotap.com for $200 so I don't take my car to dealer again for small jobs like this. If cleaning does not work I will buy Mercedes brand MAF for $440 from the dealer and still save money.
I will take photos of this job and post them for next guy who wants do this yourself. Let me know if you guys suggestions e.g. if I need to change spark plugs etc.?
Member
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From: CA
2005, E500 Designo
Where is the MAF sensor on a E500?
I bought the MAS cleaner a week ago planing on doing this job.
Is the sensor on my '05 E500 at the back of the air intake in the plastic intake tube?
Does the sensor have to be removed or can it be sprayed in place?
Are there any other sensors I could clean at the same time?
This forum is a great help.
Thanks
Is the sensor on my '05 E500 at the back of the air intake in the plastic intake tube?
Does the sensor have to be removed or can it be sprayed in place?
Are there any other sensors I could clean at the same time?
This forum is a great help.
Thanks
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From: Laguna Niguel, CA
I'm not familiar with the W211 but it has to be somewhere after the airfilter and before the throttle body and that can't be a long run on that car. There maybe two MAF sensors on the V8's, specially if you see two air filters. There's a goldish wire, usually about 1/2" long that is the actual sensor wire that needs cleaning. If you can access that without taking anything apart, you are good. It's also good to clean the entire inside of the sensor housing as you don't want dirt to redeposit itself on the wire again.
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From: New York
2001 E320
Cleaning MAF Sensor failed on 2001 E320
I bought the MAS cleaner a week ago planing on doing this job.
Is the sensor on my '05 E500 at the back of the air intake in the plastic intake tube?
Does the sensor have to be removed or can it be sprayed in place?
Are there any other sensors I could clean at the same time?
This forum is a great help.
Thanks
Is the sensor on my '05 E500 at the back of the air intake in the plastic intake tube?
Does the sensor have to be removed or can it be sprayed in place?
Are there any other sensors I could clean at the same time?
This forum is a great help.
Thanks
If you still want to try cleaning it here is some photos I took while doing the job. My suggestion, if your car drives ok and afraid of having no car for few days than don't try cleaning it instead buy one and keep it on the side just in case cleaning fails (if it doesn't fail and works make sure you can return your new MAS back). Hope this helps!
http://img407.imageshack.us/my.php?image=img1063xj6.jpg
http://img407.imageshack.us/my.php?image=img1064jd1.jpg
http://img266.imageshack.us/my.php?image=img1065gh7.jpg
http://img266.imageshack.us/my.php?image=img1069xi1.jpg
Last edited by mediasteam; Apr 29, 2007 at 08:44 PM.
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From: Laguna Niguel, CA
It appears that you are cleaning it wrong from the pictures. First, remove the MAF sensor from that tube you are holding in your hand. Usually Bosch/Siemens uses security torx screws (torx with an annoying pin in the center) to hold the sensor to the tube. Then clean the tip of the sensor (bottom of sensors in picture below) with a good blast of CRC MAF Sensor cleaner from all angles.
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From: New York
2001 E320
Thanks guys... looks like I screwed up. Now the sensor is definetely bad b/c my car RPM goes up and down. When I stepped on gas the check engine light started to blink so I did not even bother to drive just left it in the garage. I just ordered a new sensor online from http://www.alloemautoparts.com/ for $273.99 (free shipping) I ordered from them before they are great, if you do call them talk to "Ria", she's nice to work with.
They even have Mercedes brand for $364 but she said it's the same thing with different packaging.
Guys should I even try again taking apart and clean it or it's obvious that I killed it?
They even have Mercedes brand for $364 but she said it's the same thing with different packaging.
Guys should I even try again taking apart and clean it or it's obvious that I killed it?
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From: Laguna Niguel, CA
No, you didn't kill it, just probably caused dirt to sprayed on it by spraying the wrong part. Disconnect the MAF if it's causing problems, it will run fine without it. Also, clean it, get it working and then keep the spare for later use or return it.
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From: New York
2001 E320
I did not take the sensor out of the housing b/c I did not have a screw driver for it but I did spray on sensor.
I disagree that car will run fine without sensor. Yes, car runs BUT without stable rpm and will smell unburned/unused gas b/c you are not getting correct gas flow. I would not recommand anyone driving with sensor disconnected, you may face bigger problem if you do. Thanks!
I disagree that car will run fine without sensor. Yes, car runs BUT without stable rpm and will smell unburned/unused gas b/c you are not getting correct gas flow. I would not recommand anyone driving with sensor disconnected, you may face bigger problem if you do. Thanks!
MBWorld Fanatic!
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From: Laguna Niguel, CA
That's what you need to know. Trust me, I've run my perfectly running MB with the MAF sensor disconnected just for fun, most people wouldn't know the difference. If your motor is surging, unstable RPM, then your problem is not the MAF and you most likely have a vacuum leak. If that's the case, a shiny new MAF sensor would not do the trick but at least you'll have a spare.
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From: New York
2001 E320
I somewhat agree with b/c my old 1994 E320 worked almost fine with MAF disconnected but I do not think anyone will recommand doing that b/c you'll abusing your car engine. Anyway, I did not have unstable RPM issue prior to cleanning MAF sensor in my 2001 E320 so I know for sure it is sensor related. My MAF sensor has arrived today can't wait to go home and install it. I will take your advise and try to clean my old sensor again.
