Tire Pressure Monitors

[Chaz00Blue]

Now that we have had a big cold snap in NC, I am having trouble with my tire pressure monitors. At night my car sits in a warm garage, but when I'm at work it sits out all day. When I leave work I get a red screen warning me to check the tire pressures. I assume that it is caused by the fact that the air in the tires has contracted and is causing the warning. Anyone else experiencing this problem?

It's possible that I just have one monitor that is having problems. What do you think?

[Chaz00Blue]

Nobody is having this problem????

[Television]

I gave up on the pressure monitors in the wheel valves,, many cars can have the other tyre pressure monitor that works of the speed sensors in the wheels,, I know many 2003 203 cars where this has been activated on STAR so why not on your 204

[VD$]

My car displays "Correct tire pressure" warning message every time temperature outside drops. Continental low profiles tires seems to be very sensitive to temperature changes. Got this message on the screen today, went to the gas station to check - rear was -5psi, front -4psi. Checked it about one month ago. Tires on this model are far from perfect - I've changed 2 tires and fixed 4 in just one year!. On W203 I replaced only one (and it was my fault).

[peet]

If this bugs you - just go into the onscreen settings and reset your new "monitored" point of the pressure. It's not like the temps will change drastically again in a day! However, technically your tire pressure IS down right now, and when it warms up by driving it gets to the lower threshold - so add a few pounds for good measure so you're not destroying the sidewalls.

Cheers.

[who8888]

I have the same thing happened to me back couple of months ago during summer and I thought it was too hot. I reset it couple of times but it keep coming back and then I get the RED warning. I put it off for a little while longer until I found my old cheap tire pressure gauge and measured all four tires and found one of them to be really low on pressure like at 25. Drove to the gas station and use their gauge and same 25 psi showed up. Added air and the warning is no longer there. I am at VA so I get the same temp swing like you.
Go check all your tires. One of them must be really low to get the RED warning.

[Chaz00Blue]

The first time that I got the red screen, I jumped into the gas station and they were only down 1 PSI, each. I checked them again with my didgital when I got home and again they were only down 1 PSI. Maybe I have a bad pressure monitor in one of the tires.

[VD$]

I think we are in between of two fires - user manual always recommends to check tire pressure once a week and not that many people follow this rule religiously. But it was never be such an issue since W203 did not use low profile tires, that are more sensitive to temperature changes.

So we cannot blame technology too much since this is only a "messenger" and two problems are described above (unless sensor is really damaged)...

[who8888]

Well, after I posted my msg, I was heading home and guess what. I got the RED tire pressure notice. Now I know what you are saying b/c it went away by itself. Hmm.. That would stink if cold weather does cause the TPMS to go nuts

[VD$]

I saw real RED message when killed my tires twice. And it means that you have to switch to spare. It is very different than correct tire pressure and there is no chance to miss it!. What never happens to me - having RED message as “false positive”. Temperature changes (when pressure was within reasonable limits prior) generates warning only. If the message is RED, then there is a high chance of seeing a nail in the tire (tire punch may be small and computer will display only “correct tire pressure” for some time...)

[nukefixer]

Greetings,

Drove off the Mercedes dealer lot and went down the street to a tire dealer and had them replace the air in the tires with Nitrogen, google it and read up on it, I have yet to get an error tire message since then!

I learned this from my last car a VW Jetta TDI, the VW dealership recommends replacing air with Nitrogen, I even put it in my wifes Toyota Yaris........... nitrogen is the way to go!

Nukefixer

[orie]

mine has been going nuts the past week.

my car sits in the garage at night and then outside all day. I haven't seen the message pop up in the morning driving to work but 3 times this week its popped up red on the way home. I've checked the tire pressure all three times and haven't noticed any difference in pressure.

very puzzling

[jstaneff]

Thinking out loud here .....

Is it possible that there's condensate getting into the sensor and freezing? That might account for the bad readings, especially if the ice that forms interferes with the sensor's mechanism.

Of course, MB should have tested this in all their Swedish testing? Maybe, maybe not. We tend to have somewhat interesting temperature swings in the US, and that might be an untested scenario.

Dunno.

[Ron Jr]

Got low pressure warning this AM and since I had to get gas anyway I checked the pressure (all were low -5 or so) and topped off. This should be done when the tires are cold anyway and the gas station is only about 100 yards from my driveway.

[tpick23]

I read this thread last week and I am glad that I did. We moved this weekend to another house in the same neighborhood and the garage is still a mess so the cars sat outside last night. Here in NC the temp got down to the high 20s. As I got in the car I thought about reading this thread and was wandering if I would experience the TPMS issue. I have the 18" AMG style IV.

So....On start up and exiting the driveway, no red indicator. About 5 miles later it did light up. I decided to keep driving and it stayed red for 15 miles or so then went off. I did not stop the car or turn off the ignition or reset anything. It just went off.

It looks like the sensors are extremely sensitive and I think the nitrogen fills might be a good idea for these cars.

[norb]

I don't think anything is wrong with the TPMS. Tire pressure does decrease when its cold, so it will set off the warning. Then when you drive, the friction causes the tires and the air in them to heat up and increase pressure.

[VD$]

Originally Posted by norb

I don't think anything is wrong with the TPMS. Tire pressure does decrease when its cold, so it will set off the warning. Then when you drive, the friction causes the tires and the air in them to heat up and increase pressure.

I think you right - we all trying to blame the mirror. Just have to start checking tire pressure once a week as manual prescribes. The only work around can be using Nitrogen instead of air. I read a lot about this for aircrafts and event there are few folks who uses it in a car, but do not see everyone switching to it. Probably total cost of this solution is too high to consider...

[Star & Laurel]

Check your tire pressures and set to the correct pressure in the morning. When temperatures are the lowest. After setting to the pressures listed on the door / gas fill door reset sensors via dashboard. Once you do this you will not have a problem unless you have a slow leak, or a faulty sensor.

Notice how you guys are receiving the "correct tire pressure" warning now that it is getting colder? That is the only reason. Yes the sensor are sensitive, but they are just trying to prevent premature / uneven wear, or worse yet any accident. Also keep note that underinflated tires are more likely to bend / damage a wheel in the event of a rough pavement.

Nitrogen is used in aircraft because of the extremely cold temperatures they are exposed to and then immediately need to be used for landing. It is becoming more common in automotive, but is not a necessity.

[RLE]

Originally Posted by jstaneff

Thinking out loud here .....

Is it possible that there's condensate getting into the sensor and freezing? That might account for the bad readings, especially if the ice that forms interferes with the sensor's mechanism.

Of course, MB should have tested this in all their Swedish testing? Maybe, maybe not. We tend to have somewhat interesting temperature swings in the US, and that might be an untested scenario.

Dunno.

Not possible. The sensors are completely sealed in an epoxy-like material. Except for the valve stem and nothing's getting in there.

I am quite surprised at the panic level about this.

[jrct9454]

Yeah, me too....

Get a gauge; set the pressures when cold; reset the system.

Pressures will drop about 1 psi for every 8-10 degree drop in F ambient temps. No biggee.

[Chaz00Blue]

That will work, provided that the sensors do not detect an over pressure. Does anyone know how these sensors work? Do they only send a warning when the pressures are lower then the set point or do they also warn you when the pressures are high?

[jrct9454]

A good question - never heard of anyone getting alerts with overinflation, but that doesn't mean it can't happen.

Once you've reset the "baseline", there's a tolerance level - but I don't know what it is. Something sticks in the back of my mind along the lines of 10-15% from the baseline, but I wouldn't swear to that in court.

Ours have been as high as 35 psi cold and as low as 30 psi cold without a reset and without generating any warnings. Since I never let them get outside this range, my experience is limited.

[hmc]

I just had this issue addressed.

There are 2 "minimum pressure" settings in TMPS. There are by default set to what MB recommends on door panel. In my case, its 28/33, which are too high for "minimum values"

You will get warning if you try to reset a new threshold and your actual tire pressure is below these min values.

I had them changed to 25 all around and this addressed issue. Keep in mind that these are just "minimum" values. I can always reset my new threshold value anywhere above 25 w/o getting warnings. I currently set to 30/32

[Diesel Benz]

Originally Posted by hmc

I just had this issue addressed.

There are 2 "minimum pressure" settings in TMPS. There are by default set to what MB recommends on door panel. In my case, its 28/33, which are too high for "minimum values"

You will get warning if you try to reset a new threshold and your actual tire pressure is below these min values.

I had them changed to 25 all around and this addressed issue. Keep in mind that these are just "minimum" values. I can always reset my new threshold value anywhere above 25 w/o getting warnings. I currently set to 30/32

Looks like MB has been a bit too strict with the warning limits on the W204 since so many drivers get the message at cold weather. This option to tune the minimum level is a good point to remind about.

The TPMS warnings are not exactly simple. First, if you over-inflate tyres, the system would apply automatic fill detection and would autonomously set these new values for a reference (different from the older Beru system).

A soft warning is give if the pressure drops by 0.25 bar for a period of 12 minutes. If tyre pressures raise to the minimum of 0.1 bar below the set limit during this 12 minutes, no warning is given.

A pressure loss of 0.5 bar or 20% gives a hard warning. A warning is given immediately at 0.7 bar pressure loss. Above 0.7 bar the warning is delayed by 5 minutes and suppressed if tyre pressures raise to at least 0.2 bar below the reference during this time period.

If however a leak of 0.2 bar or more per minute is detected, a warning is given already before the warning thresholds are reached.

[C300SportFahrer]

Hello All,
I'm getting ready to change over to snow tires (I should of already but the wheels were on the way) The dealship here has told me that the TPMS needs to be reset via star diagnostics. I have done some searching but have yet to find anyone that had to have it hooked into the computer to reset this.

if it makes a difference i'm moving from the 18" AMGs with summers to 17" stock C300 wheels (thanks TX21!!!) with Mercedes branded sensors.

anyone else have to do this? I just don't want to have it done for no reason as well as the charge that comes with it.

thanks
Shawn

[08w204]

Don't forget to take out your "summer air" and put in the "winter air!" hahaha!

I live in Germany and there is a sticker inside the gas tank door that instructs to fill all tires with an extra 4psi for sustained driving over 100mph... I regularly set my cruise control at 115mph on the autobahn, so I took their advice. I filled to +4psi while my tires were hot and haven't had any further warnings of low PSI when the tires are cold. I know this is still technically a lower-than-suggested PSI rating by possibly 2psi while the tires are hot for sustained high-speed driving, but it seems to be working well. Unfortunately, with night-time temps in the 20's, I have to find a happy medium.

[jrct9454]

Originally Posted by C300SportFahrer

Hello All,
I'm getting ready to change over to snow tires (I should of already but the wheels were on the way) The dealship here has told me that the TPMS needs to be reset via star diagnostics. I have done some searching but have yet to find anyone that had to have it hooked into the computer to reset this.

if it makes a difference i'm moving from the 18" AMGs with summers to 17" stock C300 wheels (thanks TX21!!!) with Mercedes branded sensors.

anyone else have to do this? I just don't want to have it done for no reason as well as the charge that comes with it.

thanks
Shawn

I fail to see why the normal reset procedure as outlined in the owner's manual wouldn't work. I'd certainly give it a try before showing up at the dealership for a computer reset.

[C300SportFahrer]

Originally Posted by jrct9454

I fail to see why the normal reset procedure as outlined in the owner's manual wouldn't work. I'd certainly give it a try before showing up at the dealership for a computer reset.

Problem is, the dealership here is going to do the install, I'll try to get the SA to let me back there to troubleshoot prior to him hooking up star.
we'll see

Shawn

[joshg1001]

geez these tires are driving me crazy. they arrived at the dealer with 40+ pressure so i relieved them a bit. and just last week, the