Don’t get caught out at MoT Test time with faulty tyre pressure sensors

Posted on June 17th, 2016 by Rob Marshall


While I support technology that enhances safety, it should not replace manual checks. Tyre pressures, for example, may not be the most interesting of car maintenance chores but they are one of the most important. Tyre Pressure Monitoring Sensors (TPMS) give a driver early warning of either incorrectly inflated tyres, or a puncture. The technology started to appear on mainstream vehicles from the turn of the New Millennium, prior to becoming mandatory on all new motorcars at the beginning of last year.

The British Government views working sensors as so critical to safety, it included them within the remit of the MoT Test, on cars registered from 2012. According to TyreSafe, using data from the Driver and Vehicle Standards Agency, nearly 20,000 cars failed their MoT Tests between April 2014 and March 2015, due to faulty Tyre Pressure Monitoring Systems (TPMS). The not-for-profit tyre safety organisation accuses thousands of British motorists of failing to maintain essential road safety systems and endangering themselves and other road users as a result.

Service, not replace

On most cars, providing that a warning is not displayed on the dashboard, the TPMS system should be working correctly. However, as a sensor resides within each road wheel (on many cars), they should be serviced at every tyre change. This involves replacing the inner core and several washers and seals; most service kits should not cost in-excess of £20.00 per sensor. A typical in-wheel TPMS sensor is pictured, alongside its service kit that retailed from a main dealer at around £5.00.

Replacing sensors

The sensors themselves tend to last between eight and ten years, before replacement is due. On older cars, where TMPS is not an MoT Test requirement, it might be possible to disable the system but this is unlikely to be looked upon favourably by your insurance company. As replacing all four wheel sensors on an older car (including fitting and coding them) is likely not to be viable economically, when the car’s overall value is considered, owners of such vehicles may be relieved to hear that generic sensors are available, which tend to be neither as costly, when compared to genuine dealer-supplied parts, nor do they need specific coding to the vehicle, which saves fitting time and cost. Ask your tyre fitter for details.

Beware of the fakes

With Schrader reporting that copies of its TPMS valves are circulating on the market, which do not pass the company’s quality control tests, we would advise against buying any suspiciously-cheap sensors that might be found on some online auctions, or stores. As the integrity of the sensor guards against a sudden tyre deflation, we would argue that fitting sub-standard parts is a serious false economy and safety risk.