skullboy

I got this message yesterday on the way home, I am not sure if the tire pressure monitors are bad because I think the tire pressure is within spec for all 4 wheels of my C450 with 19 inches Continental summer tires.

StanNH

Have you tried using the pressures listed under the fuel filler door? The ones listed on the door sill are for maximum loads.

Try lowering the pressures a little and see if it corrects itself.

Cosworth2000

up the pressure...remember you are running on Run Flats..so do not allow them to loose any large pressure amounts as this will and can damage the side wall

49erPV

I keep a close eye on the tire pressure on my run flats and check them when they are good and cold and keep that pressure at 36psi on all four (fuel door spec). After they warm up, all four will vary form 39 to 41 and not all the same. I guess the key is just make sure you check when cold often and have a good gauge.

John

skullboy

This is what is on the fuel filler door that someone posted in another c450 thread. So do I go up or down my 19 inches? The thing is the other tires also are within range but are not giving off warning. I am thinking the sensors are bad.

kenya

Perhaps the reference values got screwed up somehow. Basically the car thinks the ideal tire pressure is higher that what it should be. Might be worth restarting (resetting) the tire pressure monitor. Directions should be in your owners manual.

lbowroom

Doesn't look like the sensors are failed. If they were, there wouldn't be a reading.

The only way your display would make sense if the fronts require 41 and the rears require 39.

skullboy

I just stopped by the dealer and they reset the tire pressure monitor. They told me that the monitor would throw warning for changes as little as 1 psi

tmoneyC450amg

I just had a similar problem just now except that in my case, my screen is telling me my driver side front tpms is missing??? The screen will show all 3 readings but the driver front is blank and the warning message reads "tire pressure sensor is missing" wtf?

skullboy

More than likely it has gone bad or someone stole it

tmoneyC450amg

Weird. The problem went away when I started up the car today..

MBtech764

try setting your tire pressures at 41/39 and the light should go off. If you had a bad sensor the pressure wouldn't show up for that wheel. The psi that triggers the light is adjustable, so the base psi value should be around 45/43. Its all calculated in a table in the control module. It has its base value set in the table and when the sensors show a 5 psi drop, it throws a light. You can always lower this base value, say you want the tires at 40/38, let about 5-7 psi out, reset the tpms, air them back up where you want. obviously keep an eye on them to make sure you didn't scoop up a nail er something, and remember tire psi fluctuate with temp.

Matts2015c300

I had the same problem with the TPMS on my winter set. The solution is to decide what you want as your normal pressure. In my case I run the tires at 36 psi. Then calibrate the sensors to that pressure. That's it. Nothing wrong with your sensors. I also had a sensor go and they generally just disappear from the list when they go bad. Good luck.

nvestr

Yes, there is an option to use the current pressure as the reference value I think... TRy hitting the enter button when on that screen...