Disqimation

Hi guys.
I have a 2008 s550 base model with amg wheels that came from another car that has the sport package.

The car had 285.35.19 eagle f1 runflats on the rear. I bought a pair of 275.40.19s continentals as these were the recommended tire size according to several sources. After the new tires were put on, the car drove fine for about 12 miles. I went into the store, turned the car back on and began to drive. After breaking about 10mph, the abs and esp light came on, I also lost power steering.

Now everytime I turn the car on and drive faster than 10mph, I lose power steering and thone two lights come on. My mechanic pulled the codes and he said that the abs/esp module was bad.

I'm hoping someone here can give me some insight and answer a couple of questions.

Is there any way that a tpms, steering angle or other sensor can show codes for the esp/abs module?

Could this be the result of new tires? Or is it just coincidence that my module went bad right after the tire swap?

If the problem is the control module, is it something that I can take care of without going to the dealership? Or is there possibly another remedy to the problem?

Any information is appreciated.

Thanks.

alx

So what do you have for tire sizes on the four corners?

Disqimation

245.40.19 front, came with car.
275.40.19 rear, just put on car.

superpop

I would guess it is the tires. assuming front and back tires are all new they are still 3.5% bigger in the rear. If you just replaced the rears and the fronts already have wear on them then the difference could be even worse. Do you have staggered wheels, assume so based on the size. Is this a 4matic car. If so that tire size difference is a no no. I would go to 255/40-19 in the front as that will get you under 3% in tire size difference.

Disqimation

No, it's a rwd model. The proper tire size according to tirerack is front 255.40.19, rear 275.40.19. But. I have never had these issues before the rear tires were changed.

Do you know if a tire size difference would show a code for a bad module?

ItalianJoe1

Unlikely that a code for tire size difference would cause your power steering to drop out.

Why do you not believe that the module could be bad?

If you put the car in dyno mode, do you still lose power steering? That will fully disable traction/esp and should not affect power steering at all.

Disqimation

I will try dyno mode tomorrow.

I just find it odd that the module went bad so shortly after replacing the tires.

To my understanding anytime the abs/esp error comes up, the power steering will go.

superpop

Your tires are too far apart in size. the ABS system thinks the rear tires are slipping because they are rolling slower than the fronts.

Disqimation

I will buy some 255.40.19s. Almost time for new front tires anyhow.

Could this cause the ebs module to have an error?

alx

Your car shows 255/40/19 front and 275/40/19 rears for rwd staggered setup

Between wear, wrong tires and prolly different manufacturer tolerances it is possible that your turn rate delta between front and rear is too big resulting in esp errors.

Get / borrow four donuts from dealership swap them and go for a ride- see if the behavior goes away.

AG6

i had the same issue recently. Had to replace module at dealer. Will check receipt how much that cost.

UNderdog

At 84,825 miles my ESP/ABS control unit went out and I replaced it part number 221-545-76-32 for a 2008 S65. My power steering also "went out" although it still felt somewhat assisted just not 100% - seemed strange to me at the time.

Randy

Disqimation

So I have no idea why, or how, but the lights have stopped coming on. Power steering is back to normal and everything seems to be in order.

I've literally done nothing but drive it for a while.

alx

You lost air in the taller tires... who knows ...

1bad540

Im sure it will visit you again.