Hi all,

My ML has no power, had to have it towed home today. It has been giving the P0300, P0304, P0305 and P0306 codes for the past two weeks. It had the P0170 and P0173 codes and I got a new MAF sensor and those codes went away and now this. When the misfire codes came it was when I was accelerating and from then on I can had to be careful not to press the pedal too hard. Now it shutters and won't go over 5 mph. Any ideas on what it could be?

It has 94K on thee odometer.

Here's what I've done:

CPS replaced
MAF replaced
plug replaced with bosch +2
air filter replaced

I am running out of money and stuck.[X(]

Thanks,

P.Creech

 

Hey, did you ever find out what it was that caused your issue? I'm having a similar issue with different cylinders (3,5,6). Thanks!

 

Hello and welcome to the forum! I would suggest pulling the codes first; this should give you a definitive answer as to where the issue is. Please let us know if you have any questions!

 

Sure thing, I have the codes 0300, 0303, 0305, and 0306. Unrelated but also have is 0410.

 

Have you checked your plugs and ignition coils?

 

That's what I was suspecting as well. The plugs are only 10k, so they're probably fine. I did order a set of coils and wires. Coils are all original (210k) and wires are 110k old. I haven't yet had time to pull things and check resistances though. Do you recommend anything particular for my inspection?

 

Since both parts are original, that could be the reason for the multiple misfires. I'm attaching a link to a DIY tech article from our site on the spark plug and coils replacement if that turns out to be the culprit - I know the article says it's for the C class, but it's the same guide for the ML too. Please let us know if you have any other questions!

Mercedes-Benz W203 Spark Plug and Coil Replacement - (2001-2007) C230, C280, C350, C240, C320 | Pelican Parts DIY Maintenance Article

 

Thanks! I actually have an SLK32, but yeah the procedure should be pretty similar. After I inspect the plugs and replace all the coils/wires, do you have any suggestions for next steps if that's not the issue? From my research it sounds like multiple misfires could be caused by O2 sensors or a faulty knock sensor? I'm not getting any error reporting from those units though.

 

Yes, I would definitely check the 02 and knock sensor as well - hopefully this resolves the issue.