on my 01' C320 the CEL light has come and gone recently and now has stayed on... I had AZ pull the codes and I got a Fuel Trim/misfire on Bank 2 code.
What is that?
It also idles a little rough. Not smooth anymore....

What is the service that should be done at 63k miles??? Should I change the plugs? What could the problem be. I know my wife ran regular instead of premium for a few weeks but didn't think that would do it...
Any suggestion on what it is?

 

Also, how do I reset that service indicator for the 63k miles check up?

 

Fuel Trim = MAF clean/replacement required. Common problem circa this mileage..

Search forum for MAF and you will find all about what is your likely problem SUBJECT to confirming the actual code.

Stuart

 

Thanks.... Searching....

 

So, after reading those comments, it seemd that some folks have the exact same issue as mine but my next question is: Should I replace it or clean it. Do they just go bad at this mileage or do they just get dirty att his mileage and need cleaning?

 

Hi,
Sorry to get you to search. I was in a rush last night.
Cleaning can save you some money but this process does not always work.
Since cleaning is so easy and low cost its worth a try BUT the Quality Assurred approach is a new MAF but wait till you have the codes to confirm otherwise you may waste your money.
Since the MAF and O2 sensors work together as part of the fuelling system one or the other often gets swapped out unnecessarily. The MAF determines how much fuel (+ of course many other inputs). The O2 sensor determines if the amount is correct. So it can either be the amount that is wrong OR the O2 sensor used to measure the amount doesn't read correctly.
Simply really.

To remove the sensor you may need a special security Torq screwdriver bit. A few pence from good auto shops.

stuart

 

Ok, I have the codes at home. I will get them and post them up tomorrow and we will see what it could be then,
Thanks

 

The code is P0173 so definately either a REALLY dirt air filter, which is possible because we have a gravel driveway or a Dirty MAF or bad MAF.
Thanks for the help...

 

Almost certainly the MAF.
Stuart

 

FROM My post on D.I.Y.

OK this D.I.Y. Post should aid you in a couple reapairs on your 2001 C240, but should apply to the 1999-2005 c240's as well.

Background before starting, my Check Engine light was on and my indications from the car were poor pickup or slugglish/surging acceleration. Like it wants to go smoothily but then choked a bit. After the car warmed up it wasnt so bad, but still present. Also my Codes given were Bank 1 Fuel Trim & Bank 2 Fuel Trim.

Replacing your MAF - AMM - MAS (Mass Air Flow - Air Mass Meter - Mass Air Flow : Sensor)

I did all 3 of these today. I have no experience with a Mercedes Benz, just a good working background in Mechanical work. It took me 3.5 hours to do all 3 repairs. I used a mechanics bay at work, that is provided by the Army. All tools and lifts.

Also I am NOT a MECHANIC, but these techniques should work for your c240. If you find any errors in this guide please post, it only helps us all.

ONE LAST THING. After I reconnected my battery I got a ESP MALFUNCTION - ESP - Electronic Stabiliy Program Not found or Not installed.

To correct this. Start the car. turn your wheel full left, then full right, then full left. Turn off the engine, and restart.
This technique Reprograms the ESP.

TOOLS Needed:
1 - Standard Flat Head Screw Driver
1 - 10mm socket and socket wrench and 10" Extenstion if you so choose.

Parts Needed:
1 MAF (Will be refered to as MAF for the rest of the post)

REPAIR:
Use the 10mm Socket wrench and remove the Negative and Positive Cables.

Remove the plastic intake tubes, just compress the tubes and they pull off.

Remove the front Engine cover. Pull the end closest to the front up the car up then toward you.

Remove the Rear Engine cover. Pull Up the front and then the rear end.

Remove the plastic ring around the top of the MAF.

Unplug the MAF

On the Back of the MAF there is a metal clip, I used my finger to pry it back, but you could use a screwdriver.

Remove the MAF and replace with new one.

Reconnect the Cable.

Attach Plastic Ring.

*At this point you can reconnect your battery and see if
your check engine light is still on.

DONT ERASE YOUR CODES BEFORE STARTING!!!
Ok if the MAF is the cause of your CEL (Check Engine Light) then it will go out on start.
(Keep in mind that your allowing unfiltered air into your engine so this should only be used for a quick check)

If your CEL doesnt go out your MAF may not be the problem.
Now that this is finished you would reinstall all covers and Done!