Fixed Idle: Replaced Air Mass Sensor (MAF)
02-21-2007, 12:32 PM
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2005 SL600 by SPEEDRIVEN
Fixed Idle: Replaced Air Mass Sensor (MAF)
Two weeks ago my car threw a check engine light (CEL) and had a hard time keeping a constant idle at 600 when I would come to a light. It would drop to almost 0 and then spike to 1000 trying to reach a constant idle rpm. It seemed to drive fine once it was going but coming to a stop and then starting again was exasperating to say the least. The car would most likely die.
From reading others posts the problem appeared to be the Air Mass Sensor ("AMS") also know as the Mass Air Flow Meter ("MAF"). Sure enough the OBDII code was P0100 for the MAF or VAF circuit failure. Others have referenced codes P0170 - Fuel Trim Malfunction (Bank 1) and P0173 - Fuel Trim Malfunction (Bank 2). However, I didn't see these codes. You can have the OBDII codes pulled for free at AutoZone or Checker.
I removed the old AMS (MAF) in around 20 minutes. The steps are as follows:
(1) Remove the front engine cover with the Mercedes star on it by pulling up.
(2) Remove the left and right air intake tubs that run into the air filter box.
(3) Pull up on the air filter box which is held in place by four ruber gromets.
(4) You will then see the AMS (MAF) at the back of the engine.
(5) Unclip the plug on the right hand side of the AMS.
(6) Unclip the left and right plastic arms of the ring that holds the AMS onto the engine block. It can and should be completely taken off the AMS in order to more easily remove the AMS from its holding tube.
(7) Use a flat head screw driver (longer is better) and push the metal clip away from the AMS (the clip is attached to the holding tube) so that it can be firmly pulled up and out of the holding tube. I had to wiggle it back and forth gently and up at the same time. It took some effort but it does just slide out. You may notice that the tube it plugs into, which goes into the engine may also move when you try and remove the AMS. Do not take this part off- only the AMS should come off.
(8) Reverse putting the parts back on (this took about 1 minute).
Fired the car up and it immediately idled properly. After three cycles of starting and shutting the car off the check engine light disappeared. Problem solved.
I purchased the AMS from autopartswarehouse.com which price matched Importecparts.com in the amount of $191.00 (price included free shipping). The Dealer quoted me $384.00 for the AMS alone and then install was over an hour at their hourly rate. What a rip off! Everyone should do this repair themselves and put the saved cash into other modifications.
I have attached a picture of the AMS, which is deal part#1130940048 for the 2001 CLK55 AMG.
From reading others posts the problem appeared to be the Air Mass Sensor ("AMS") also know as the Mass Air Flow Meter ("MAF"). Sure enough the OBDII code was P0100 for the MAF or VAF circuit failure. Others have referenced codes P0170 - Fuel Trim Malfunction (Bank 1) and P0173 - Fuel Trim Malfunction (Bank 2). However, I didn't see these codes. You can have the OBDII codes pulled for free at AutoZone or Checker.
I removed the old AMS (MAF) in around 20 minutes. The steps are as follows:
(1) Remove the front engine cover with the Mercedes star on it by pulling up.
(2) Remove the left and right air intake tubs that run into the air filter box.
(3) Pull up on the air filter box which is held in place by four ruber gromets.
(4) You will then see the AMS (MAF) at the back of the engine.
(5) Unclip the plug on the right hand side of the AMS.
(6) Unclip the left and right plastic arms of the ring that holds the AMS onto the engine block. It can and should be completely taken off the AMS in order to more easily remove the AMS from its holding tube.
(7) Use a flat head screw driver (longer is better) and push the metal clip away from the AMS (the clip is attached to the holding tube) so that it can be firmly pulled up and out of the holding tube. I had to wiggle it back and forth gently and up at the same time. It took some effort but it does just slide out. You may notice that the tube it plugs into, which goes into the engine may also move when you try and remove the AMS. Do not take this part off- only the AMS should come off.
(8) Reverse putting the parts back on (this took about 1 minute).
Fired the car up and it immediately idled properly. After three cycles of starting and shutting the car off the check engine light disappeared. Problem solved.
I purchased the AMS from autopartswarehouse.com which price matched Importecparts.com in the amount of $191.00 (price included free shipping). The Dealer quoted me $384.00 for the AMS alone and then install was over an hour at their hourly rate. What a rip off! Everyone should do this repair themselves and put the saved cash into other modifications.
I have attached a picture of the AMS, which is deal part#1130940048 for the 2001 CLK55 AMG.
02-21-2007, 07:36 PM
#2
MBWorld Fanatic!
[P0170 - Fuel Trim Malfunction (Bank 1) and P0173 - Fuel Trim Malfunction (Bank 2).]
Turns out that, 95% of the time, these are the OBDII codes for a MAF problem. The other 5% of the time could be a vacuum leak etc..
[I removed the old AMS (MAF) in around 20 minutes. The steps are as follows:]
On a CLK320, it took a couple of minutes and a screw driver.
You don't have to take off the engine, air box cover etc..
1. Undo the (2) spring retaining clips (between the air box cover and the MAF. The top one with your finger, the bottom one may need to be released by pushing down with the screw driver.
2. Using the screw driver loosen the hose clamp on the other end. Disconnect the electrical connecter and remove the MAF.
Install the new MAF in reverse order.
[After three cycles of starting and shutting the car off the check engine light disappeared.]
True (as descibed in the owner manual).
However, if your coming up to a state inspection....BEWARE.
Most states now use OBDII readings to determine the emission test. Even though the CEL is out (and your car runs like new).....the OBDII 'status ready' readiness takes about 300 miles of driving for the OBDII sensors to go from 'not ready' to 'ready'. YOU FAIL if any of the status sensors are 'not ready'.
Turns out that, 95% of the time, these are the OBDII codes for a MAF problem. The other 5% of the time could be a vacuum leak etc..
[I removed the old AMS (MAF) in around 20 minutes. The steps are as follows:]
On a CLK320, it took a couple of minutes and a screw driver.
You don't have to take off the engine, air box cover etc..
1. Undo the (2) spring retaining clips (between the air box cover and the MAF. The top one with your finger, the bottom one may need to be released by pushing down with the screw driver.
2. Using the screw driver loosen the hose clamp on the other end. Disconnect the electrical connecter and remove the MAF.
Install the new MAF in reverse order.
[After three cycles of starting and shutting the car off the check engine light disappeared.]
True (as descibed in the owner manual).
However, if your coming up to a state inspection....BEWARE.
Most states now use OBDII readings to determine the emission test. Even though the CEL is out (and your car runs like new).....the OBDII 'status ready' readiness takes about 300 miles of driving for the OBDII sensors to go from 'not ready' to 'ready'. YOU FAIL if any of the status sensors are 'not ready'.
02-24-2007, 12:55 AM
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2000 CLK 430 Cabriolet
Hey thanks, ashutt. $191 is cheaper (but not by much) than the one I saw. I gotta get mine on soon (I have NO symptoms but pulling bad codes so I can't get thru emissions in MD).
02-25-2007, 11:38 AM
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02 CLK55, 07 E92 335 ProCede
I simply replaced the MAF sensor from bosch, without the whole housing. The total cost was 105 and I installed it myself.....Got rid of the same codes the car threw....here is a pic of how it looks on ebay
http://cgi.ebay.com/ebaymotors/MASS-...QQcmdZViewItem
http://cgi.ebay.com/ebaymotors/MASS-...QQcmdZViewItem
