TPMS Light!!!

[Ash977]

I have a 2006 BMW X5 4.8is. The TPMS light in the dash goes off when driving for about 45min at Hwy speed in 90 degree heat... I checked the tire pressure after the car sat overnight. The front is set at 32 and rear at 34. I reset the TPMS several times. After the car sits for a while the light goes way and doesn’t come back on until it is driven for an extended time at Hwy speed again. Any idea what is wrong????
Thanks a lot,

[killcrap]

The EHC2 control unit disrupts CAN bus signals going to the DSC control unit. The DSC control unit determines when to turn on the flat tire warning. Check the fault memory in the EHC2 control unit, perform the test plan if the CAN fault is present. It will advise you to install an updated control unit.

If no faults are stored for CAN bus, then most likely you have not provided us with enough information. Such as... If your air struts are leaking, or if the traction control lamps are on.

[Ash977]

Killcrap – Thank you for your help. I will take it to my indy shop to have him scan the EHC2. As far as other info you mentioned, I have no other lights on in the dash. None of the struts are leaking air. I had the lower control arms, tension bars, and bushings replaced about a month ago. This TPMS light situation started after these parts were replaced. However, the heat and high humidity in LA started around the same time.

[killcrap]

do you ever go to your doctor, and tell him your stomach hurts, and you ask him what could possibly be wrong with you? and then once he tells you what he thinks it is, do you tell him that its been hurting since you ate an AA battery?

like I said, you probably did not provide enough information to us. I know you would not like to place blame on the recent installation of thoes parts, but lets be smart about it.

[Ash977]

Thanks Killcrap – Interesting way of putting it…
However, could you please explain to me how the lower control arms and bushings can affect the rotation of the wheels only when the temperature is over 90 degree and driving for over an hour at Hwy speed? It sounds like a faulty sensor that is sensitive to high temp to me…

Thanks again,

[killcrap]

the dual air suspension system uses 4 hall effect sensors to determine ride height. there is 2 sensors in the front on the lower control arms. if this sensor is not installed correctly it can cause various issues. the arm on the sensor should look like an human elbow at 90degrees, and the hands at the bottom.

[Ash977]

Killcrap – Thank you for the explanation. I will check on that when I get home today.

[BabyCAP]

Your pressure will increase due to the high temps. Then at night the temp decreases and tire pressure drops. The sensor may pick this up and issue a warning. What you want to do is re-set the warning and then drive immediately after re-set. This way the sensor calibrates to the pressure when you did the re-set.

FYI - I am in DC with hot and humid temps. I parked in airport lot for a weekend trip (visiting Cali !!!!) When I return it is raining and overcast. Drive off lot and get a warning. Check pressure with gauge and all good. Re-set button and have been good since.

IMO It's your amazing West coast weather that may be the culprit. You had a heat wave last week or so and that might be the cause.

[killcrap]

Originally Posted by BabyCAP

Your pressure will increase due to the high temps. Then at night the temp decreases and tire pressure drops. The sensor may pick this up and issue a warning. What you want to do is re-set the warning and then drive immediately after re-set. This way the sensor calibrates to the pressure when you did the re-set.

FYI - I am in DC with hot and humid temps. I parked in airport lot for a weekend trip (visiting Cali !!!!) When I return it is raining and overcast. Drive off lot and get a warning. Check pressure with gauge and all good. Re-set button and have been good since.

IMO It's your amazing West coast weather that may be the culprit. You had a heat wave last week or so and that might be the cause.

only vehicles with direct tire pressor monitoring suffer from temperature issues, no USA made E53 comes with this system.

[Roadkill]

Originally Posted by BabyCAP

Your pressure will increase due to the high temps. Then at night the temp decreases and tire pressure drops. The sensor may pick this up and issue a warning. What you want to do is re-set the warning and then drive immediately after re-set. This way the sensor calibrates to the pressure when you did the re-set.

FYI - I am in DC with hot and humid temps. I parked in airport lot for a weekend trip (visiting Cali !!!!) When I return it is raining and overcast. Drive off lot and get a warning. Check pressure with gauge and all good. Re-set button and have been good since.

IMO It's your amazing West coast weather that may be the culprit. You had a heat wave last week or so and that might be the cause.

this is incorrect information for the problem the op has described. as killcrap stated this is an eletrical fault. i just went through this exact same issue myself. bmw has built heating/cooling related flucuations into the TPMS system so that the light is not illuminated everytime you drive. if your logic was the culprit, the middle of this country and the heat they have to endure during summer would cause bmw to issue a recall on a grand scale.