BobbyT

On my 2012 E350, the yellow tire pressure warning light (resemble the cross-section of a tire) comes on every few days. I have reset it several times, and have checked that the tires pressures are correct as specified on the fuel filler door. The warning light came on again yesterday, and when I checked the pressures via the TPMS, it showed 29-29-33-34.

Is this system that finicky, or is there a defect?

CEB

What are the correct pressures? Are you using the OE wheels with OE sensors?

enzo thecat

Maybe this will help Post #13 was the solution.

https://mbworld.org/forums/e-class-w...ure-range.html

theraven333

These pressures are all low !!! Plus the 2012 E class works on a rotational basis, not air pressure directly. It detects the air loss by the change in rotational height, so put the correct pressures in ( when totally cold, warm tyres naturally have higher pressure) and then rest the system!!! if after a couple of days you check the pressures and they are down (again cold tires) then you may have a leak/loss of pressure!!!

BobbyT

Oops, my bad. I misstated the tire pressures in my initial post. The pressures in the tires are front 35, rear 36, as specified on the fuel filler door for normal load. The wheels and tires are factory original 17" with about 8,000 miles on them. The car is US "Luxury" model. With those pressures, the tire pressure warning light keeps coming on...

BenzV12

Hey try this :

Lower all the pressures and set them at 30 psi . Reset the TPMS according to that pressure and then after it's all set again inflate the pressures up to desired value . Mine works well and no more warning light comes on.
I can confirm that tpms works efficiently , I have seen twice these warning on my cluster and each time there was a problem with the tire (1st pressure loss due to stud , 2nd curbed the pavement lol )

Why I run my pressure higher than register ? Because of eliminating possibility of false readings from various reasons .

Nuru

smart move, smart move. I think i may have to do the same thing. Don't know why I did not think of doing that myself.

Johnny Mo

My TPMS seem to be reading 4-5 psi high compared to my accupressure digitial tire gauge...not sure what that's about, but I'm not quite sure what the fix is either.

Live Oak

In my opinion, TPMS is good ONLY as a change warning indicator. But it's very good at that.

I set my tires, cold, with a quality tire gauge. Then I reset the TPMS. I don't care what pressure the TPMS shows (within reason) because I know what the real pressure is.

I don't get false warnings, but if an incident happens --- a nail, or when cold weather hits --- I'll get a proper warning --- fix the flat, or crank up the air for winter weather.

BobbyT

Okay, I now have a decent tire gauge (Joe's Racing 32307) so I can set the tire pressure more precisely. I set the tire pressures cold at F35, R36, and reset the TPMS. I will report back when/if the warning light goes off again, and the pressures shown. The car is due for its first service next month, so I plan to collect some good data before then.

Live Oak

>>>>>>>. "I now have a decent tire gauge (Joe's Racing 32307)" <<<<<<<<<

That's a great gauge. I've tested it against others, and find it equal to the most expensive. Well made, the rubber cladding makes it tough, it has a great dial, a good valve interface, and it's absolutely consistent, which is the most important thing.

BobbyT

Thanks, Live Oak, for the information on the tire pressure gauge. The TPMS shows two psi lower than the gauge, so it is good to know that the gauge may be more accurate.