RS6 C7 Tyre pressure warning keeps activating

[OliB]

Hi, I have a 2015 C7 RS6 and the tyre pressure warning keeps activating. When I look at settings in MMI, it seems to be activating every time there is more the 0.1 Bar difference between the two front tyres or between either back tyre. I keep adjusting tyre pressure to be the same and reset the stored pressures, but every few days when I start the car the warning appears again, when there is 0.2 Bar difference when tyre are cold. Very frustrating. Any one else had this or know of a fix possibly to reduce sensitivity?

[AT.]

For me a 0,1-0,2 Bar difference in just days seems to be a problem, as it's about 5-10% loss in the pressure in a very short period. Are you sure your tyres are OK?

[OliB]

Presures are going up an down, so it's not a leak.

[AT.]

Look, I don't want to argue with you on obvious things

What I intend to mention was a feeling. For me, such a difference ON ONE CAR, in some days, between the same tyres seems to be a failure. If you think, your tires are OK, then it could be even a TPMS fault. IMHO, as all the A6/C7 related cars have the very same system, and as far as I know, no one had a problem like this with their system, IMHO it's not a useful thing to try to expand the tolerance of the tyre pressure difference, but IMHO it's better to find the reason why you have this fault message almost day-by-day.

But it's my IMHO, please do not take it as a harassement.

To be short, no, I have no idea on how you can increase the tolerance.

[diecastsink]

My MY12 A6 there can be 0.3-0.4 bar difference without need for storing new values.
I keep she on +15 C carage during winter, and ride at some -20..30 C and it has never made an alarm.

To iterate the fault, some things to consider:
- do you have actual pressure value shown in MMI? if not, like in EU models then:
- if it appears when cold, all tires should have equally low pressure
> no difference in front/front, rear/rear or front/rear, right? should not give alarm
- of only both rear pressures are changed by 0.3-0.4 (like mine when using trailer with raised rear prsssure)
> it won't give an alarm. (standard 225/55-17 can make difference, guess you don't have donuts in RS (lucky you...)
- i think it would give alarm if only one tyre pressure is different - not for diff in front/rear
- have you made any changes/replace brake pads, detached wheels etc?
- check if the ABS sensors are correctly aligned, it could make it more sensitive if the sensor is having poor signal
- check cable looms and connectors
- put some pressure in both front and then some .5 or so more in rear, store values and check if this makes difference
- do the same otherway round, check
- check all brake stuff is ok
- have you got any vibration (unbalanced wheels or damaged rims)? > check weighting and alignment
- check bolts are tighten
- swap front/rear tires, check
- check with different suspension settings
- check any fault codes
- reset MMI
- reset ABS module ( don't know if that is possible
- restore any VCDS tricks made especially for brake module, if any

Keep record what you have tried, otherwise you cannot track what would be the combination which affects the fault.

[AT.]

- do you have actual pressure value shown in MMI? if not, like in EU models then:

It sounds interesting!

Is there any VCDS trick to allow the MMI to show the actual values? I always wondered, why the TPMS does not show these figures. It was very annoying when I saw the warning message, and I didn't knew the exact values.

[A6S]

It sounds interesting!

Is there any VCDS trick to allow the MMI to show the actual values? I always wondered, why the TPMS does not show these figures. It was very annoying when I saw the warning message, and I didn't knew the exact values.

I believe there's 2 versions of tpms.
One that uses the abs sensors as a flat tyre will rotate slower than one full of air so there's actually no way of telling pressure. It's just letting you know that there is a difference in pressur. This is standard on all uk cars.
The other version has actual pressure sensors inside the wheel or at the valve. Never seen these in the uk.

[AT.]

This is standard on all uk cars.

I have an EU version, and it has the same system. By this, probably the US versions have real TPMS.

It's just letting you know that there is a difference in pressur.

In this case it's not telling you the pressure problem, but a constant rotating difference. which can be anything (if the pressure is ok). So by this, it can be an ABS sensor failure, a brake failure, or even a transmission problem. It's good to know, that if it shows a failure, then you better check your tires asap, and if there is no problem, you should find the actual problem before it could became worse.

[diecastsink]

There seem to be three kind of systems, Direct measurement with sensors installed onto wheels (Siemens, Beru) and indirect by abs sensors depending on market area. Also RS6 seem to have always direct system at least in 4F based on document from few years back.
image.jpg
image.jpg
Doc can be found from erwin, maybe there is newer one including 4G RS6.

[artheb]

I have an EU version, and it has the same system. By this, probably the US versions have real TPMS.



In this case it's not telling you the pressure problem, but a constant rotating difference. which can be anything (if the pressure is ok). So by this, it can be an ABS sensor failure, a brake failure, or even a transmission problem. It's good to know, that if it shows a failure, then you better check your tires asap, and if there is no problem, you should find the actual problem before it could became worse.

If there was an issue with ABS sensor then VCDS scan should tell you exactly which sensor is faulty. However faulty sensor would also trigger ESP, Start Stop, ABS and TPMS errors in the same time.
OP: Do the VCDS scan and see if you get any sensor errors.