Do I have a TPMS system on my vehicle

Do I have them and how do they work.

All new vehicles produced after 2015 must have some form of Tyre Pressure Monitoring System (TPMS).

There are two types of system: Indirect which uses the cars

ABS system - it can tell that one tyre is dragging compared to the other one on the same axle, which it then flags up on the dashboard as a problem.

This could be down to a puncture, general low air or as I have seen, a different sized tyre fitted (giving a different rolling diameter).

This system is often found on older BMW's, and still on most of the VW group (VW, Skoda, Audi, Porsche).

One problem with the Indirect system is that both tyres on the same axle could slowly lose pressure right down to zero, but because they are both dragging the same, the system doesn't call it up as a problem.

The other system is Direct TPMS, this involves having some form of battery-operated sensor fitted between the tyre and the wheel rim. These are generally attached to the valve, but I have seen a sensor wired to the centre of the rim. Approximately 70% of the ones fitted to valves are fixed to a metal valve, the rest are fitted to a rubber valve, so its not always possible to tell from the outside if a sensor if attached or not.

Most of the sensor types give a reading to the vehicle's computer every 3 seconds, and it is often possible to see on the dash exactly what pressures are in each tyre. This system is much more accurate than the indirect system. Whenever you have a tyre removed, to be replaced or for a puncture repair, then you should reset the system before you drive. On some vehicles this means you have to press a button, or go into the vehicles computer and select tyre pressure reset, although some vehicles reset the system automatically every time the engine is started. Ideally you need to read your cars manual to see how your system works.

The problems with the Direct system are that because they are battery operated, there becomes a time when the battery dies, and the system fails. Since the sensors are mostly sealed for life, then they must be replaced (The average life expectancy is 5 to 7 years, but can be shorter on high mileage vehicles). Another problem is that because it is part of the valve, then whenever you change tyres, you should have the sensor serviced. This involves replacing the valve stem and the sealing nut. This adds around £10 to £15 per wheel. (Not something everyone budgets for, and not something all tyre depots offer as a service). If you don't service the sensor, then the rubber sealing parts perish and you will lose pressure from the valve.

Additionally, since the change in the law in 2015, then these sensors must work for your vehicle to pass its mot. Older vehicles will pass the mot with a failed sensor, and it is called up as an advisory only.

We at Hometyre can service your sensors whenever we change your tyres, as we carry a comprehensive stock of replacement parts for these sensors, both the rubber and metal types. We also have replacement blank sensors, which we can programme to your vehicle using our on-board diagnostic equipment. That way the vehicles computer doesn't even know the part has been replaced.