TundraRoads

My wife's ML350 has begun giving her a strange tire pressure warning. The TPMS comes up on the screen in all red and beeps. The left front tire pressure is in reverse text (e.g., black number in red box). However, all tire pressures, including left front, indicate normal pressure. All tire pressures, including left front, are changing as normal (lower at first, go up by 2 or 3 psi as you drive). So, all sensors SEEM to be working.

Any thoughts on what this could be?

MB dealer wanted her to drop the car off for them to look at it. She's tired of dropping her less than year old car off at the dealer to get problems fixed and dealing with their loaner car program. I asked if they could first check to see what they could find out about a common problem like this and if they could just swap the sensor. SA said they can't do either, have to leave the car.

skw

What exact pressures is it showing her? I have had mine for only 2 days so far and getting the warning as well. It's showing my driver's side rear tire at 42psi and the oters at 40-41. I have to go by the dealer tomorrow anyways but my initial thoughts are that maybe it's too high. I would think that somewhere around 35-36 as a cold pressure (adjusted first thing in the morning) should be suitable. I adjusted mine today and we'll see if it does anything.

GregW / Oregon

Use the pressures on the fuel filler door. That's too high for the front, especially. Unless loaded, try 32F and 36R and you'll see how much more comfortable it is. Not sure if that would trigger the TPMS, though.

awjenni

I had the same problem with the tire pressure monitoring system (TPMS) within an hour of leaving the dealer with my brand new 2012 ML350BTC (on June 23rd). The display beeped, turned red, and showed the tire pressure readings... and all of them looked good. I restarted the TPMS (per the instructions in the manual, p. 361) and it has been fine ever since. The readings on all of the tires are always within a pound of each other.... around 32-33 when starting up in the. Gets up to around 36 on a hot day of driving. Al

twodivers

Folks - don't forget - once you adjust the pressures, reset the TPMS for the new settings so that it knows they are the "default" or correct ones. If you adjust down to 32, but do not reset the TPMS (and it was set prior to delivery for 40), it will likely throw the warning!

stenney71

Has anyone had an issue with the TPMS not matching the tire PSI? I've only had my 2012 ML350 for a couple of months and has 2000 miles on it. My TPMS alert shows my tires at 30-32 psi but when I check the tires manually they are at around 38 psi. I haven't reset the TPMS yet, that's my next step but just curious if anyone had seen discrepancies like this.

serge01

started shopping for winter tires today and was told by a dealer that there is not tire pressure monitor inside the wheel so i do not need to by anything for my winter rims. Is this true?

nosnoop

For Canada, yes, as there is only passive TPMS.

serge01

thanks nosnoop