I always scan my 2004 clk320 every month or so to make sure I don't have any problems. Well, today I just recieved a P0221 code. Can anybody help me as to what the problem is please? I remember a few months back I had a MAF code but can't remember what the problem was. I've heard it may be the throttle body being dirty but who knows. Thanks

 

It's a problem in the electronic throttle pedal itself. You could try the "resync" procedure below, but it's probably going to need a new pedal assembly:

1. Make sure everything in the car is turned off and closed.
2. Turn the key to position 2 so all the dash lights are illuminated.
3. Press the accelerator fully to the floor, depressing the "kick-down" button.
4. Hold he pedal for 5 seconds and continue to hold it down.
5. Turn the ignition switch back one click to position 1.
6. Release the accelerator pedal, but leave the key in position 1.
7. Sit quietly and wait for about two minutes - do NOT open or turn anything on.
8. Listen for a "click" or "ping" noise form the dash.
9. Start the engine and drive the car for at least five minutes.

 

Do you have the part number by any chance? I'll try it tomorrow morning, thanks a lot Rudeney!

 

Should this resync procedure be performed periodically?

 

The part number is VIN-dependent as there were several revisions, plus the difference between sport package or not.

As for performing the resync, some people claim it can restore quicker throttle response or problems with odd shifts. I have never noticed that it does anything on my cars. Basically, what it's doing is re-calibrating the travel range of the pedal with that of the electronic throttle body. I suppose various things could cause them to get out of sync, like normal wear of the moving parts.

 

Isn't this re-sync procedure the same as the one to reset the transmission?

 

Many people do refer to this as a "TCU reset", but it does nothing to the TCU. I think that much of the effects of the resync are placebo. I guess that of the throttle were out of sync, the TCU could be reacting to a pedal input that does not match the throttle, so you might get some odd shifts.

 

My understanding was our transmissions adapt to our driving habits and the shift points would change according. This reset procedure would remove the adaptation and start with factory setting..

Please correct me if I misunderstood.

 

I do not believe that procedure will reset the transmission's adaptive learning. Maybe it does, or maybe it;s just that it changes throttle behavior so it has to do some re-learning. There are many functions within SDS that can be used to erase the adaptive learning or even to sort of "hard code" the shifts. It's pretty complex, so I doubt it would be as simple as the throttle reset to clear all that.

 

I just erased the code on my scanner. Should be fine right now. If it shows up agin on my scanner I'm going to have to replace it. Thank a lot for the help.