TPMS Error

[sm1287]

So since my 5000 mile service (I now have 20k miles) I have been getting the TPMS error and the low tire pressure light. I have been to the dealership repeatedly to get this checked out and all they do is reset the lights and check the tire pressure. Everything checks out, but without fail within the next day or so the errors come back. Is this common? I'm considering taking it to another shop that's not at the dealership b/c all they seem to want to do is reset the error and not really look into why it comes up. Any advice?

[doug97gxe]

my wife's started doing this every other week after she got a new tire.. i just keep resetting it.. she has a compressor in her trunk so i'm not worried and the tires seem to be fine

[RAF_S7]

Have a look at this (current) thread:

http://www.audizine.com/forum/showth...t-wont-go-away

[sm1287]

Have a look at this (current) thread:

http://www.audizine.com/forum/showth...t-wont-go-away

Awesome thanks, I had limited my search to just the A5/S5/RS5 forum. I'll expand my search in the future.

[JamesRS5]

The A5 doesn't use pressure sensors inside the tire, it uses the ABS sensor to detect the number of rotations of the wheel.

A dumb check but did this happen after fitting a new tire or fitting the spare wheel and are all the tires the same size?

If you have VCDS you can check the ABS sensors for wheel speed to see if one is reading low.

[doug97gxe]

The A5 doesn't use pressure sensors inside the tire, it uses the ABS sensor to detect the number of rotations of the wheel.

A dumb check but did this happen after fitting a new tire or fitting the spare wheel and are all the tires the same size?

If you have VCDS you can check the ABS sensors for wheel speed to see if one is reading low.

in my case .. yes they are all the same size.. my wife had a nail and i ordered 1 from tire rack to replace it .. actually now that i think about it.. it started doing it more than 6 months after the tire was replaced

[sm1287]

The A5 doesn't use pressure sensors inside the tire, it uses the ABS sensor to detect the number of rotations of the wheel.

A dumb check but did this happen after fitting a new tire or fitting the spare wheel and are all the tires the same size?

If you have VCDS you can check the ABS sensors for wheel speed to see if one is reading low.

For me this started happening after I first set the correct pressure in the tires for the first time on my original tires from factory. Continued happening after I got my tires replaced. And happened after the dealership checked the tire pressures in all 4 tires and set the correct pressure.

[Jeff V.]

The A5 doesn't use pressure sensors inside the tire, it uses the ABS sensor to detect the number of rotations of the wheel.

My 2008 S5 has actual sensors in the wheels. I'd presume early A5s are similar. Audi changed it in either 2009 or 2010. I'm not 100% sure which.

I had to have one of my sensors replaced because the o-ring was leaking, triggering a periodic TPMS warning.

[phroenips]

in my case .. yes they are all the same size.. my wife had a nail and i ordered 1 from tire rack to replace it .. actually now that i think about it.. it started doing it more than 6 months after the tire was replaced

If the tread depth is a decent amount different on that one tire, that would cause that one wheel to roll ever so slightly slower than the other three. And that could trip the TPMS since it's going off of the ABS sensor and how fast each wheel makes a revolution in relation to the other wheels.

[doug97gxe]

If the tread depth is a decent amount different on that one tire, that would cause that one wheel to roll ever so slightly slower than the other three. And that could trip the TPMS since it's going off of the ABS sensor and how fast each wheel makes a revolution in relation to the other wheels.

this actually makes sense to me.. apart from Audi and electronic issues.. but thanks.. this is probably what it is

[jschrauwen]

My 2008 S5 has actual sensors in the wheels. I'd presume early A5s are similar. Audi changed it in either 2009 or 2010. I'm not 100% sure which.
I had to have one of my sensors replaced because the o-ring was leaking, triggering a periodic TPMS warning.

Hi Jeff
I too have the physical 315mhz sensors in each wheel as well on my 2008 A5. I've reset my MMI TPMS and also cleared the code/message via VCS but it always comes back right away. I suspect that the batteries in one or more of my sensors are beginning to fail since their expected battery life is something like 6 to 10 years.
I have 8 new sensors to install - 4 for my oem wheels and 4 for my winter wheels that never had any.
Would you happen to know the broad strokes of the replacement procedure so that I don't get taken to the cleaners at my Audi shop? I believe I read that they need to be programmed and/or coded in first or something to that effect.
Any help or direction or links to assist would be appreciated.
Cheers

Attached are my new sensors.
15977338_10154350404203613_4087424888749673974_n.jpg
16003051_10154350404453613_636360174283366912_n.jpg

[superswiss]

If the tread depth is a decent amount different on that one tire, that would cause that one wheel to roll ever so slightly slower than the other three. And that could trip the TPMS since it's going off of the ABS sensor and how fast each wheel makes a revolution in relation to the other wheels.

It's actually not that simple. The first versions of indirect TPMS did what you describe. They only measured relative wheel rotation speed. Problem with that was they could only detect if one tire was low. If all tires lost pressure at the same rate, it wasn't detected. The latest generation system Audi uses is much more complicated. It measure oscillations in the wheel assembly that are highly influenced by tire pressure and performs a digital signal analysis to determine if pressure is low. It can detect low pressure in all four tires. Slight differences in tread wear should not make a difference as resetting TPMS starts an about 20 minute learning cycle to measure all these oscillations and to set a baseline for comparison. Once the baseline is set, then it can detect a 20-25% deviation on any of the four tires. If the system keeps going off for no reason, then something is faulty with the electronics or your wheel assembly. I would start with getting the tires road-force balanced to make sure they are rolling as good as they can. If that doesn't solve it, then more investigation is needed.

A bit more information on indirect TPMS can be found on Wikipedia and other sources: https://en.wikipedia.org/wiki/Tire-p...#Indirect_TPMS

[RockJGC]

It's actually not that simple. The first versions of indirect TPMS did what you describe. They only measured relative wheel rotation speed. Problem with that was they could only detect if one tire was low. If all tires lost pressure at the same rate, it wasn't detected. The latest generation system Audi uses is much more complicated. It measure oscillations in the wheel assembly that are highly influenced by tire pressure and performs a digital signal analysis to determine if pressure is low. It can detect low pressure in all four tires. Slight differences in tread wear should not make a difference as resetting TPMS starts an about 20 minute learning cycle to measure all these oscillations and to set a baseline for comparison. Once the baseline is set, then it can detect a 20-25% deviation on any of the four tires. If the system keeps going off for no reason, then something is faulty with the electronics or your wheel assembly. I would start with getting the tires road-force balanced to make sure they are rolling as good as they can. If that doesn't solve it, then more investigation is needed.

A bit more information on indirect TPMS can be found on Wikipedia and other sources: https://en.wikipedia.org/wiki/Tire-p...#Indirect_TPMS

Where is the sensor that measures these oscillations that you're describing? I'm asking because I thought it was strictly the wheel speed sensors that were used for TPMS.

[superswiss]

Where is the sensor that measures these oscillations that you're describing? I'm asking because I thought it was strictly the wheel speed sensors that were used for TPMS.

I take it you didn't read the Wikipedia article I linked to, because it answers that very question. There is no new sensor. You are correct, these oscillations get picked up by the existing wheel speed sensors and can be monitored through advanced signal processing of the wheel speed signal. That's why I'm saying it should be looked at. If TPMS is on the fritz, ABS could be on fritz as well, because they use the same electronics. The TPMS algorithms are integrated into the ABS system.

[Jeff V.]

Hi Jeff
I too have the physical 315mhz sensors in each wheel as well on my 2008 A5. I've reset my MMI TPMS and also cleared the code/message via VCS but it always comes back right away. I suspect that the batteries in one or more of my sensors are beginning to fail since their expected battery life is something like 6 to 10 years.
I have 8 new sensors to install - 4 for my oem wheels and 4 for my winter wheels that never had any.
Would you happen to know the broad strokes of the replacement procedure so that I don't get taken to the cleaners at my Audi shop? I believe I read that they need to be programmed and/or coded in first or something to that effect.
Any help or direction or links to assist would be appreciated.
Cheers

Attached are my new sensors.
15977338_10154350404203613_4087424888749673974_n.jpg
16003051_10154350404453613_636360174283366912_n.jpg

I couldn't find any relearn process in the factory ELSA documentation. It only shows how to do the physical install. So I'd guess the relearn procedure is built into the VAS diagnostic software.

I did find this page, showing how to do it if your car has a module 65 / J502. Mine does. You need VCDS to do diagnostics, but it looks like matching new sensors is as simple as letting the air out of the tires and then letting the car sit with the ignition on for 20 minutes.

http://wiki.ross-tech.com/wiki/index...on_Recognition