Pristine

The tire pressure light come on the dash yesterday and it is not going away. I've checked the pressure few times and it seems to be OK (30 psi front / 34 psi back).

Any idea what might be happening? Does it only display if the pressure is too low or also when it is high?

joshg1001

It doesnt check for low, it checks for changes.

You could have it really high and it dropped down to normal and the light would come on.

Suggestion: go to a gas station and measure it with the tires relatively cold and then when you got it all right, push the steering button "right" all the way into system (past navi, audio, telephone). Then under the menus, you can find tire pressure reset and if you click "OK" it will reset it and memorize the current tire pressure you have just set.

vic viper

It comes up at regular intervals, just check the pressure and reset.

Pristine

OK, thanks.

Illusive

On a similar topic, does the W204 have TP sensors inside the wheel or does it measure the rotational speed and backwards calculate for the diameter to determine if there is a decrease in size and therefore pressure?

Savage c-300

there are TP sensors inside. this feature actually saved me a couple weeks ago. Since I have low pro tires, its hard to tell if I'm running flat or not. Good thing these babies were able to detect the change in air pressure.

jrct9454

There was, at least for the '08 W204s, a different answer for this in Canada vs the USA:

Canadian cars got the indirect TPMS [based on rotational speed]; USA cars got the direct system, with sensors buried in each valve.

Unless something's changed for '09....

nyca

Others may disagree, but I cannot use the "reset" mechanism via the trip computer to baseline the inflation pressure more then 3 psi below the recommended inflation pressure on the door. So if its 35psi for the rear, if the rears aren't at least 32psi, the calibration reset will work for a while, but the light will then come back on.

nyca

Another point - when you engage the reset via the trip computer screen, let it fully go through the process. There is a point on the screen where you think its complete, and you might then press the OK button. Don't do that, once you engage it - let it complete and then return to the previous screen by itself.

RedG

As stated direct TPMS, also ALL cars sold in the United States from 2009-on are REQUIRED to be equipped with tire pressure monitors.

Spec_Davis

can it be done without TPMS on the car?

joshg1001

...are you sure, even hyundai's and such?

Illusive

Well a good way to tell is if your valve stem is metal or rubber. If its rubber, its definitely rotational as there is no support for such a device. If its metal, then its a sensor inside. Mine are rubber...

vic viper

Easy to check if you have the "real deal" Tire Pressure Monitor, check your vehicles datacard 470 or 475 means TP sensors in your wheels, 477 means RPM dependant TPM.

Norm01

Well, now you guys have me interested. I have 477 and I was going to buy winter tires and rims and was looking at purchasing 4 TPM sensors. Based on what I just read, I do not require TPM sensors?

vic viper

Correct.

Also I think that you can read out the actual pressure in the IC display with code 470 or 475 TPM.

CEB

...Europe uses a different system from the US....

The American TREAD act requires direct pressure measurement (currently implemented on most cars using sensors in each wheel) as opposed to the RoW that uses a combination of existing sensors to determine the rotational diameter of the wheel. As the pressure goes down, the diameter of the tire changes. This is called the indirect system.

There are a few problems with the indirect system - first, the system needs to be calibrated by the driver and, if the pressure was wrong when calibrated, will not read accurately. Secondly, since the system looks for changes between the tires to determine if one is leaking, it does not show seasonal variances....

Diesel Benz

Not quite correct...

Europe is using both the ESP based tyre pressure loss warning system as well as the one using sensors in the wheels. Our operating frequency on the sensors is different though.

Of course the low cost RDW-option isn't as good as the real RDK or TPMS option, they would not have both if the cheaper one would do everything the more expensive one does.

ctgilles

Eh... Mercs have actual sensors but BMW's still use the rotational method iirc (eg. E60/61)

nukefixer

Datacard, is that the plate on the side of the drivers door with tire pressures etc?

Diesel Benz

No, he means the document that describes everything about that vehicle. I understand the US "Window sticker" comes close to this but isn't exactly a data card. You can get the data card from EPC (and some other sources) against your VIN.

You can try from the Russian site too (if your car is not too fresh for them).

http://old.mbclub.ru/mb/vin/?lng=eng

RedG

BMWs also have direct TPMS from 2009-on. In point of fact MOST BMWs (save the M-series cars) have run flat tires even from 2005 on, which means BY DEFAULT from the factory they are equipped with a direct TPM system.

Yes, it is MANDATORY on every passenger and light truck from 2009-on, even Hyundai's.

Illusive

Only in the US. Read the manual and all Canadian W204's have the rotational TPM.

Kuwago

I have c230 Kompressor 2005 I dont have tpm is there any intall a tpm to this model?...need help..

racetested

An old post being brought back up actually helped me (I say this as some people get irritated from old topics be re-hashed).

Anyways with my winter tires on my "tire pressure light" kept coming on and I just dealt with it for the time being. I had no idea the factory wheel tire pressures were built into the system to set off the "warning". I assumed different tires could be used and then set the indicator to monitor those pressures(my winter wheels/tires being all the same size and same pressure opposed to staggered like the OEM set-up).

A full day later no light as I set my winter wheels to the factory pressures. Fingers crossed.

I assumed the monitors Tirerack installed in my winter set-up maybe weren't fully compatible but the problem now seems to be fixed.