Please Correct Tire Pressure
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C63S
Please Correct Tire Pressure
After ~30 minutes of driving today, I got a message saying "Please Correct Tire Pressure" and it identified the two front tires. What's odd is the tire pressure identified is certainly not low and I don't think would be high enough to trigger the message if too full (if that's even a thing). It identified the two front tires as 43-44 psi (rears at 41). That seems to me to be a bit high (despite what the door jamb sticker says) which is odd as I haven't filled them in a while and it's cold now so would think the tires would be losing pressure.
Is there such a thing as too full and it will give that message? And if so, I wouldn't think it be at the current indicated psi?
Is there such a thing as too full and it will give that message? And if so, I wouldn't think it be at the current indicated psi?
MBWorld God!
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The front tire being hotter and/or higher tire pressure especially the front right was probably due to the oil cooler dumping hot air.
As for being too much pressure, it wouldn't tell you (other than just telling you to please correct tire pressure) but you will clearly feel that something is wrong.
The tire pressure is predetermined by you or the dealership setting it as what is the acceptable value. You can change the tire pressure and then reset it so it learns the new values.
Instead of the door jamb sticker, you may consider using the fuel door sticker. Remember to always check your tire pressures when tires are cold/not driven for a couple of hours.
As for being too much pressure, it wouldn't tell you (other than just telling you to please correct tire pressure) but you will clearly feel that something is wrong.
The tire pressure is predetermined by you or the dealership setting it as what is the acceptable value. You can change the tire pressure and then reset it so it learns the new values.
Instead of the door jamb sticker, you may consider using the fuel door sticker. Remember to always check your tire pressures when tires are cold/not driven for a couple of hours.
Out Of Control!!
Joined: Nov 2018
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From: San Francisco Bay Area
2019 C63CS
As said above, there is no predefined correct pressure. You have to go into the Service menu and reset TPMS after you've adjusted your cold tire pressures to the desired pressures. If you've never done this then who knows what it's currently set to. Also as mentioned, the pressure on the door sticker in the USA is not what you wanna be using. Those are for a fully loaded car and driving speeds over 155 mph. The correct pressures to use can be found on the sticker inside of the fuel door. They are lower for normal load and speeds of <= 155 mph.
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C63S
Thanks for the responses. I went ahead and dropped all 4 tires by a few PSI and then reset the "reference point" in the Service menu to those current values.
What's odd is that the previous pressure level that caused the warning light to come on was not a crazy level or a new level. It's not like I had just inflated them more and crossed that threshold. I can't recall the last time I put air in and I haven't driven much over the last few weeks so the car has mostly been sitting in the cold and thus, if anything would be losing a little pressure. I don't know what PSI was set in the Service menu, but that would seem to me to be irrelevant anyway since I hadn't adjusted tire pressure recently so nothing has changed and I'm not sure why I would all of a sudden get that notification when I hadn't on other recent drives.
I have had an issue with settings being forgotten so I do wonder if somehow the car reset the "reference" values (in Service menu) itself. That would be a first for tire pressure. I have had the car reset (on its own) my "individual" driving mode settings a handful of times.
What's odd is that the previous pressure level that caused the warning light to come on was not a crazy level or a new level. It's not like I had just inflated them more and crossed that threshold. I can't recall the last time I put air in and I haven't driven much over the last few weeks so the car has mostly been sitting in the cold and thus, if anything would be losing a little pressure. I don't know what PSI was set in the Service menu, but that would seem to me to be irrelevant anyway since I hadn't adjusted tire pressure recently so nothing has changed and I'm not sure why I would all of a sudden get that notification when I hadn't on other recent drives.
I have had an issue with settings being forgotten so I do wonder if somehow the car reset the "reference" values (in Service menu) itself. That would be a first for tire pressure. I have had the car reset (on its own) my "individual" driving mode settings a handful of times.
Out Of Control!!
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From: San Francisco Bay Area
2019 C63CS
It's likely the cold temperature. Every drop of 10F is a 1 psi drop in tire pressure, so if they were last inflated when it was warmer then you would now potentially be several psi lower just due to the colder temperatures, not accounting for the natural loss of pressure. Then on top of that a typical tire can lose 0.5 to 1 psi every two weeks due to loss of air. I check mine every 14 days and I'm usually about 0.8 psi low w/o much change in ambient temperature. So over the course of a month it would be closer to 2 psi lost. You really need to check the tire pressure regularly on these cars, and especially if you have large swings in ambient temperature. Also, the TPMS sensors are not the most accurate and only have a 1 psi resolution. You should use a more accurate digital tire gauge.
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C63S
Yeah, I get that pressure will drop with cold and with time. But that would make sense as the cause if they dropped to a low level. But I have definitely (and usually) had them lower (by several PSI) than the 40+ that it was reading when the light came on. So in that case, the light should have come on all of those other times too.
It was also identifying the two front tires as the problem even though those were a few PSI higher than the rears that were not indicated to be a problem. My assumption there is whatever the Service menu setting was had the front values higher than the rears which is why the lower PSI rears weren't identified as needing adjustment.
Again, unless the car reset the threshold values on its own, I don't know why the light came on when I have certainly previously had lower PSI than it was reading when the light came on. I wonder if the relatively limited recent driving caused the battery to drop to a point that weird settings changes can happen. I think that was the cause of my previous loss of individual driving mode settings. It seemed to happen when it had been a bit since I drove the car for a decent distance.
It was also identifying the two front tires as the problem even though those were a few PSI higher than the rears that were not indicated to be a problem. My assumption there is whatever the Service menu setting was had the front values higher than the rears which is why the lower PSI rears weren't identified as needing adjustment.
Again, unless the car reset the threshold values on its own, I don't know why the light came on when I have certainly previously had lower PSI than it was reading when the light came on. I wonder if the relatively limited recent driving caused the battery to drop to a point that weird settings changes can happen. I think that was the cause of my previous loss of individual driving mode settings. It seemed to happen when it had been a bit since I drove the car for a decent distance.
