TPMS busted??

N55_BBM · 08-29-2011, 09:42 AM

Hey guys, tracked the car on Saturday, optimal pressures for me on my PSS 225/255 were 40 front and 38 rear. Drove back home (5hr drive) and parked for the entire night.

Next morning when I drove off to run errands I got a low pressure warning from my left rear. Normal I thought since the tires probably cooled down substantially. When I got back I got my pressure gauge out, indeed the tire was at 32psi and the other ones weren't far off. Bumped the pressure back up to 38psi all around and parked overnight.

This morning I drive off to work and the left rear low tire pressure is still there. So when I got to work I measured all 4 tires and they're all still at 38psi.. no leaks or anything.. I tried that "reset" button on the onboard computer but the warning doesn't go away.

At this point I'm not sure if I'm somehow failing to reset the sensor or what. I've had a low pressure warning before and it went away after I adjusted the pressure so I'm not sure what I'm doing wrong.

Also, how do I diagnose whether it's a problem with the computer or the TPMS itself if it doesn't go away? These are my Alufelgen CS7s which I got on the group buy, so I'm assuming the TPMS that they put in there isn't the stock one and I can't pull off getting the dealership to replace it for free?

wolfe · 08-30-2011, 06:56 AM

I may be way off on this but I think when you reset the sensor, it uses the current tire pressure as the new 'baseline'. Depending on how long your drive is I would maybe try resetting it when they're cold(er).

I had some weirdness with mine a while back, I had forgotten to plug a front sensor back in after removing the wheel arch liner. Even after getting it all hooked back up it took a while to get back to normal behavior.

For what it's worth, on the alufelgen CS7 group buy thread I saw someone posted pics of the TPMS they received. They appeared to be made by BERU, which is the OEM supplier to BMW. From what I can tell they're exactly the same part as the ones BMW uses, only without a roundel printed on them and cost less.

N55_BBM · 08-30-2011, 07:09 AM

I am a complete idiot and did not realize I had to reset the warning thing once I got the pressure back up.

Problem solved, disregard this thread!

08-29-2011, 09:42 AM	#1
N55_BBM Major 96 Rep 1,038 Posts Drives: 2011 135i Coupe Join Date: May 2010 Location: PA iTrader: (1)	TPMS busted?? Hey guys, tracked the car on Saturday, optimal pressures for me on my PSS 225/255 were 40 front and 38 rear. Drove back home (5hr drive) and parked for the entire night. Next morning when I drove off to run errands I got a low pressure warning from my left rear. Normal I thought since the tires probably cooled down substantially. When I got back I got my pressure gauge out, indeed the tire was at 32psi and the other ones weren't far off. Bumped the pressure back up to 38psi all around and parked overnight. This morning I drive off to work and the left rear low tire pressure is still there. So when I got to work I measured all 4 tires and they're all still at 38psi.. no leaks or anything.. I tried that "reset" button on the onboard computer but the warning doesn't go away. At this point I'm not sure if I'm somehow failing to reset the sensor or what. I've had a low pressure warning before and it went away after I adjusted the pressure so I'm not sure what I'm doing wrong. Also, how do I diagnose whether it's a problem with the computer or the TPMS itself if it doesn't go away? These are my Alufelgen CS7s which I got on the group buy, so I'm assuming the TPMS that they put in there isn't the stock one and I can't pull off getting the dealership to replace it for free?
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08-30-2011, 06:56 AM	#2
wolfe Captain 134 Rep 613 Posts Drives: e82 / e70 / r56 / r60 Join Date: Apr 2010 Location: USA iTrader: (1)	I may be way off on this but I think when you reset the sensor, it uses the current tire pressure as the new 'baseline'. Depending on how long your drive is I would maybe try resetting it when they're cold(er). I had some weirdness with mine a while back, I had forgotten to plug a front sensor back in after removing the wheel arch liner. Even after getting it all hooked back up it took a while to get back to normal behavior. For what it's worth, on the alufelgen CS7 group buy thread I saw someone posted pics of the TPMS they received. They appeared to be made by BERU, which is the OEM supplier to BMW. From what I can tell they're exactly the same part as the ones BMW uses, only without a roundel printed on them and cost less.
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08-30-2011, 07:09 AM	#3
N55_BBM Major 96 Rep 1,038 Posts Drives: 2011 135i Coupe Join Date: May 2010 Location: PA iTrader: (1)	I am a complete idiot and did not realize I had to reset the warning thing once I got the pressure back up. Problem solved, disregard this thread!
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