Tyre pressure monitor driving me mad

[emagstar]

I just bought an approved used 2018 UK Polo last week.

On the way home, the tyre pressure warning light came on complaining about the front right tyre pressure having dropped. I pulled into a petrol station and checked all the pressures and noticed the front right was 2psi higher than the other tyres. I understand the tyre checking system uses the abs to determine if one tyre feels different to the rest and throws the warning so I let some air out so the pressure was the same across all four tyres, reset the warning and continued to drive home.

Just before I got home the warning triggered again, I checked the tyre pressures again and all were the same, so I reset the system again. The system then went on to thrown the warning fives times over the course of the week! Each time I check and reset its driving me mad. Today I took the car to a garage to check for any very slow leaks and none were found. I have now booked the car into vw on wednesday, hopefully they can get to the bottom of it.

Has anyone had a similar expericence with a 2018 onward polo?

[monkeyhanger]

Sounds like a dodgy ABS controller. The ABS unit measures differences in rolling circumference - a flatter tyre has a smaller rolling circumference.

[emagstar]

Sounds like a dodgy ABS controller. The ABS unit measures differences in rolling circumference - a flatter tyre has a smaller rolling circumference.

Yeah I thought it might be a problem with the ABS, but I don't have an ABS warning light?

Could it be a wheelspeed sensor that the ABS uses?

[RUM4MO]

Yeah I thought it might be a problem with the ABS, but I don't have an ABS warning light?

Could it be a wheelspeed sensor that the ABS uses?

That will be up to your VW dealership to find out, guessing is not a good idea, just book it in and get it sorted I'd think is the best idea.

[Simonz]

I've had the same problem, also a 2018 early model. Could be some problem developing with the sensors due to age or the car battery beginning to lose capacity?

[emagstar]

So VW couldn't find anything wrong, no errors had been logged. They pumped the tyres again and did a hard reset of the tyre monitoring system. The only other thing they mentioned is one of front tyres has just been replaced so each front tyre does have a different tread depth. They thought this could be triggering the warning. Anyway it triggered again today so I assume that is the most likely cause... Guess I am just going to have to keep resetting it.

[monkeyhanger]

So VW couldn't find anything wrong, no errors had been logged. They pumped the tyres again and did a hard reset of the tyre monitoring system. The only other thing they mentioned is one of front tyres has just been replaced so each front tyre does have a different tread depth. They thought this could be triggering the warning. Anyway it triggered again today so I assume that is the most likely cause... Guess I am just going to have to keep resetting it.

They're s**t you there. The TPMS measures differences in values stored for each wheel's rolling circumference (loss of pressure = smaller circumference). New tyre or not, if you've reset the TPMS since fitment, unless the circumference has changed (loss of tyre air pressure), the TPMS should not be flagging an issue.

Same wheel flagged every time? Try swapping the fronts for backs and see if same wheel still flags. Probably a dodgy sensor with the car being unaware it's a false flag.

Another possibility is an increase in rolling circumference due to a spike in ambient temperature - temperature proportionally affects pressure in a closed system (like a tyre). There'll be some expansion tolerance - the difference between a cold tyre and a warm tyre (been used on a journey) is 3 - 4 psi. if your PSI has gone up by a little more than that because of a very hot day and in use vs cold pressure, that could trigger it.

[emagstar]

So VW couldn't find anything wrong, no errors had been logged. They pumped the tyres again and did a hard reset of the tyre monitoring system. The only other thing they mentioned is one of front tyres has just been replaced so each front tyre does have a different tread depth. They thought this could be triggering the warning. Anyway it triggered again today so I assume that is the most likely cause... Guess I am just going to have to keep resetting it.

They're s**t you there. The TPMS measures differences in values stored for each wheel's rolling circumference (loss of pressure = smaller circumference). New tyre or not, if you've reset the TPMS since fitment, unless the circumference has changed (loss of tyre air pressure), the TPMS should not be flagging an issue.

Same wheel flagged every time? Try swapping the fronts for backs and see if same wheel still flags. Probably a dodgy sensor with the car being unaware it's a false flag.

Another possibility is an increase in rolling circumference due to a spike in ambient temperature - temperature proportionally affects pressure in a closed system (like a tyre). There'll be some expansion tolerance - the difference between a cold tyre and a warm tyre (been used on a journey) is 3 - 4 psi. if your PSI has gone up by a little more than that because of a very hot day and in use vs cold pressure, that could trigger it.

Yeah to be honest I though the tread depth explanation was rubbish.

So the last few times it has triggered, it didn't specify which wheel was the problem, it just highlights all four wheels. When it does specify which tyre its always the front right so swapping the tyres isn't a bad idea! I might try that if they claim there's nothing wrong again tomorrow.

It has been a few hot days here, but nothing crazy. The system has also been reset during the hot weather so I can't imagine it is just temprature.

Its happend twice more since yesterday so I have booked into VW again tomorrow. Its getting really frustating!