I have an early build SL55 (in service date of January 2003). About a month ago I started getting wacky readings off one of my tire pressure sensors (left front), usually showed 5 - 6 pounds higher than actual. Reset accomplished nothing. The others were fine. After pressuring the dealer (I had an extended warranty) got the sensor replaced. Everything worked fine for a while. Now the rear sensors are acting up (same symptoms, real high pressures). Just yesterday I got a message of "Tire pressure monitor, go to shop". Reset doesn't bring anything back. I am interpreting this to mean that one or more of the batteries in the sensors are gone. However, it could be the computer. The odds say the sensors, but with Mercedes electronics God only knows.

I'm thinking about getting all new sensors from the Tire rack (people on this forum have reported good experiences with them) as their prices are about 25% of what Benz charges (Benz charges $350 PER SENSOR, these are, at most, $75 parts). If I change all the sensors and it works, happy ending. However, if it is the computer, and I have to go back to the dealer and deal with the extended warranty hassles, I may make matters worse for myself as they might try to weasel out of paying for any repairs because I used "unauthorized parts" (even though those parts are identical to the ones Benz buys for OEM use).

The reason I just don't go the dealer upfront is that, because of the way the insurance works, they will replace as few overpriced sensors as possible, any of them giving off a signal will be left alone. But, given that two have failed, it's obvious that the batteries on these things don't last more than 5 years, and the prudent thing to do would be to replace them all. That probably won't happen if I go the dealer route.

Anyone been through this on the particular car? Have people seen this message before when one or more sensors fail? Anyone ever have the TPMS computer fail? If so, what were the symptoms?

 

Just got new tires and sensors installed. Got the sensors from the Tire Rack. No luck. Getting a red message (which requires a restart to clear) about checking the tire pressure. Have reset the system five or 6 times. What comes next? Something required from the dealer? Let ti set overnight and hope for computer magic relearning?

Any suggestions?

 

Did you wait for the reset procedure to finish? It can take a while.

If you did that then the system needs to be read-out to see what causes the red message.

I'm guessing the red message is US car specific since the errors I get when TPMS has problems (e.g. when changing winter/summer tyres) is in the normal color. Red (with alert sound) is reserved for serious problems.

Either that or you have a more serious problem.

 

I waited for the reset procedure to finish. It usually takes about 15 minutes. It just didn't work. I checked all of the tires manually, they are all fine.

I spoke with a dealer and a workshop today and they both tell me that I need to go to a shop and have them use a "SDS" computer to tell the car about the new sensors. Since two shops have the same story maybe this is real. I'd like to find out more about this procedure.

 

Found an old sensor in the trunk, it was screwing up the reset.

Whenever you need new TPM sensors, and you will (batteries), deal with Luke at the Tire rack.

About 25% the price of dealing with your "authorized" dealer.

A painless procedure.