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2005 SLK 350
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75 Posts
Discussion Starter #1
My ML has been working perfectly up until a couple of days ago when after an hour on the freeway it started to loose power and feel like it was going to stall. At first the problem was intermittent since I drove it to the shop later that day and it worked fine. Now it isn't going anyway under its own power. The shop read the codes but couldn't bring it into the shop until Monday. Right now it idles fine (maybe a little rough) but when I push on the throttle, the engine rpm dips and then accelerates. If I try to drive it, it hesitates, acts like it will stall and then surges. I'm having the ML towed to the shop but want to make sure it isn't something simple before I through a bunch more money into it. Five DTC came up when I read them (P0170, P0173, P0450, P0460 and P0700). I checked the fuel cap and cleaned the MAF already (didn't help). Here are the code definitions:

P0170/173: Fuel trim malfunction banks 1&2
P0450: EVAP Emission control system pressure sensor fault
P0460: Fuel level sensor A circuit malfunction
P0700: Transmission control system malfunction

The symptoms had a sudden onset after an hour of working perfectly. They were intermittent at first but are now constant. Anyone have any thoughts? I have a new fuel filter and MAF insert on order from germanstar dot net, just in case.
 

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24 Posts
Hey, i'm having the same problems, and only both the fuel trim codes. I see no one replied but if you got it fixed can you tell me what happened?
 

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Outstanding Contributor
02 ML320 06 ML500
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17,350 Posts
Sounds like you have a dirty Mass Air Flow Sensor. It is located in the air intake hose (big accordian hose). Remove the plug and then remove the two torx screws and pull it out. DO NOT TOUCH an part of the interior end of the sensor. Look at the thin wire on it and you will see black soot attached to it. By a spray can of CRC Mass Air Flow Sensor Cleaner and spray the wire until all the soot is gone. DO NOT TOUCH THE WIRE. Let it dry completely and reinstall the sensor.

After you have done this procedure clear the codes with a scanner or disconnect the negative battery cable for a few minutes and see if any codes return.
 

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500SE AMG, E350 4matic, GL 450
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5,914 Posts
Like 43sqd said, clean the MAF. That should take care of P0170 and P0173. I am not familiar with the other code.
 
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