I have a 1998 ML320 with just over 133k miles. Recently it has started to act up. The check engine light came on and I checked the codes. It showed me the MAF was bad and showed a few misfire codes. I replaced the MAF and the codes were gone. I also replaced the air filter. Shortly thereafter (few days) the CEL came back on. I checked the codes again and it showed me 0460 p/d (pending), or the fuel sensor. Each time I erase the codes and then restart the truck it runs fine. But when ever I put a load on it either by going up a steep hill or quickly depressing the pedal (punching it) it starts to knock/ping, loses power and the CEL either flashes or just comes on. I believe the truck is going into limp mode... Now the 0460 code seems to be gone. (someone suggested keeping the tank more full), but it is still showing 0300, 0304, 0305 and 0306. Again turning the truck off seems to resest the limp mode... Short of taking my checkbook to the dealer can anyone suggest what I might do? Any help would be appreciated. Thanks.

I've been doing a lot of reading here and I am convinced the problem is something electrical. Maybe the throttle position sensor? I noticed I don't need to contact the button switch under the gas pedal for this issue to occur.

 

What kind of gas are you using in your ML? Was your car ever updated with high flow fuel filter? How good is your air intake filter? Check all the basics before your trip to dealer. Bernard

 

I agree with mbenz80 that you should change the fuel filter. If this has not been done before, the new filter is larger so you will have to change the2 fuel lines that go from the tank to the filter and the 1 outlet line. This is available as a conversion kit from MB.

If this does not eliminate the 0300 series of codes, the ECM may be the problem. The 0304, 0305 etc. codesare just misfires in the corresponding cylinders. I stumbled onto the fix for my 98 ML320. The ECM is located right behind the underhood fusebox on the driver's side. I disconnected it completely and took it off the vehicle to replace it with a used one. The used one did not work and MB claims that the ECM cannot be re-programmed for the vehicle and that they are VIN specific and have to ordered new, direct from MB at approx. $2000, which is exorbitant so I did not order it. After the old ECM sat for an hour off the vehicle, I re-installed it and all codes were gone and the ML ran fine for another 6 months til I sold it. This may or may not work on yours. Good luck.

 

be very very careful when going to a MB dealer - my experience is they are catastrophic!!!! - the fact you pay does not mean your car is fixed!!! - this form seems to be excellent and i have just emailed -chassis221- a question - he professes to be a certified MB master - try him out