Mass Air Flow Sensor SL500

[Red SL]

Recently I change my air filters, SL 500 2001, I happen to be in AutoZone and they offered 3 types paper filter, and I took the cheaper one, for no real reason, three starts later the check engine light came on. I took it to a shop the code showed Mass Air Flow Sensor/MAF. They gave me a price of $642 and $72 for installation. Now, I can obtain the part for just under a $150.

I removed the 2 AutoZone filters, I install new Mann filters, and on the second trip the engine light came back on. I am ordering a new Air Mass Flow Sensor . It seems simple to install. Seeking inputs!

[jplinville]

No input on the install...just the filter. At anytime, did you use an oiled filter? If so, don't ever do it again. The oil will play hell with the MAF.

Stick with what Mercedes recommends, and you should be fine.

Also, I've heard about some of the cheaper filters not being the correct size, and allowing contaminates into the intake system...

[SunGuy]

Originally Posted by Red SL

Recently I change my air filters, SL 500 2001, I happen to be in AutoZone and they offered 3 types paper filter, and I took the cheaper one, for no real reason, three starts later the check engine light came on. I took it to a shop the code showed Mass Air Flow Sensor/MAF. They gave me a price of $642 and $72 for installation. Now, I can obtain the part for just under a $150.

I removed the 2 AutoZone filters, I install new Mann filters, and on the second trip the engine light came back on. I am ordering a new Air Mass Flow Sensor . It seems simple to install. Seeking inputs!

Did you try cleaning your existing sensor inside the round housing, with either electical cleaner (essentially alcohol, available at RadioShack) or CRC brand MAF Cleaner(alcohol based, available at PepBoys, AutoZone, NAPA, etc) I did mine a couple years ago and expected only a temporary solution until I'd have to buy one. So far, the MAF operates flawlessly, and I clean it annually when I change the air and dust filters. As long as the wire and film are intact in the sensor itself, it should clean up. To inspect, you'll need a T-20 TorX Tamper Resistant screwdriver or bit to unscrew the two screws holding the sensor to the MAF housing. Good luck and have fun-

Bob

[jdonnee]

I have a 96 SL500 with two K&N oil based filters and have never had a problem with the MAF. I have also never cleaned my MAF. That is a great suggestion.

[Red SL]

OK, thanks SunGuy you made a great suggestion. I stop by Wal-Mart and pick up a can of electrical cleaner, I removed the complete assembly, I did not get the screwdriver, and I almost exhaust the complete can of cleaner on the MAF sensor. I reinstalled it and reset the engine light (by unhooking the battery hot wire, I realize the code may not be cleared). I have driven the car for two days and no engine light.

I will continue monitoring it, I still have the new MAF sensor coming in $150, it will be on the shelf or I may return it for 20% restock fee unless someone else needs it.

[96C220]

Originally Posted by Red SL

OK, thanks SunGuy you made a great suggestion. I stop by Wal-Mart and pick up a can of electrical cleaner, I removed the complete assembly, I did not get the screwdriver, and I almost exhaust the complete can of cleaner on the MAF sensor. I reinstalled it and reset the engine light (by unhooking the battery hot wire, I realize the code may not be cleared). I have driven the car for two days and no engine light.

I will continue monitoring it, I still have the new MAF sensor coming in $150, it will be on the shelf or I may return it for 20% restock fee unless some else needs it.

OBD II cars "self clear codes"

Basically there is a 3 good trip formula. If you take 3 trips over 10 miles, and the flaw does not return, the code goes away.. When you clear the memory, you have to wait for "readiness" codes to set, basically in laymans terms the car has to be driven enough for the ecu to decide that its time to monitor the sensors objectively.

George

[jdonnee]

Do you need to take the sensor out to clean it with the MAF cleaner or can you just spray it in the MAF opening like cleaning an old carb.

[96C220]

Originally Posted by jdonnee

Do you need to take the sensor out to clean it with the MAF cleaner or can you just spray it in the MAF opening like cleaning an old carb.

I'd take it out... You really want to spray what ever comes off plus the cleaner upstream of the intake path?

[SunGuy]

I'd do as George suggests, remove the sensor with the two TorX screws or the entire MAF. In mine, '99, there is a wire mesh secondary cover on the MAF itself that prohibits spraying the sensor without removing either of the above...even with a tiny straw connected to the cleaner nozzle, it still wouldn't go through. That said, other model years may be different.

Bob

[jdonnee]

I'm just not comfortable trying to remove it. Besides, I am not sure I know what it looks like.

[Larry Delor]

SunGuy,
The screen is held in by a giant spring clip. Just get something thin enough (like a utility knife, for instance) started on the one end of the clip, and run it around until the clip pops out.

jdonnee,
I don't know for sure what yours looks like either, but it would have to be just before the throttle body, and most likely have some sort of protective screen on it.
---- I just looked it up on Fastland - it looks pretty much like the one that SunGuy has, except yours is all plastic. If you have a security bit set, you can remove just the insert, and not replace the sleeve as well.

Then again, if the cleaner worked, all this is a moot point

Good Luck!

[Red SL]

It has been over two months since I cleaned the MAF and I have not had another light. I passed emission life is good.

[trawler pilot]

I have 90 500SL with 34000 miles. Car exhibits all symptoms of mass air flow sensor including check engine light. I can not locate this part. I want to clean it before buying another. Any help? Would stoofpilot by chance be S2F? I'm in ILM also.

[benhogan]

Just clean your MAF with MAF-specific cleaner and don't use K and N filter.