Brussels – An EU campaign group has issued a report accusing car-makers of manipulating “indirect” tire pressure monitoring systems (TPMS) to pass laboratory tests, even though the devices might not perform reliably on the road.
Despite meeting current official requirements, the indirect systems mostly failed during on-road tests commissioned by Brussels-based Transport and Environment (T&E) – an umbrella group for transport and environment NGOs in Europe.
Two vehicles with indirect TPMS and under-inflated tires, a VW Golf and a Fiat 500L, “performed as required in a copy of the narrow type approval test carried out by automotive testing specialists Idiada,” said T&E.
However, the report went on to note that “out of 16 real-world tests diverging from the official protocol, the Golf failed 14 and the Fiat all 16.”
When the same regulatory test was repeated on tires with some mileage; the TPMS failed to alert drivers of tires’ low pressure, the campaign group further claimed.
This, argued T&E, indicates that the indirect systems were primed to get through official tests but become less sensitive once they were used on the road.
The organisation further alleged that carmakers could be optimising indirect systems to be less sensitive after the initial test.
Indirect systems, explained T&E, rely on tire vibration and wheel rotations to detect low pressure. As such, it said, they are less effective than direct TPMS, which have sensors to accurately measure the pressure in each wheel.
Vehicle makers “could be deploying defeat devices to get ineffective tire pressure monitoring systems to pass safety tests and save themselves €10,” claimed Julia Poliscanova, clean vehicles manager at T&E.
She called for investigations into “suspicious TPMS performance”, saying T&E’s tests showed indirect TPMS systems were “unsafe”.
EU law has mandated the use of TPMS systems in new passenger car vehicles since 2014 but doesn’t differentiate between direct and indirect systems.
ERJ is awaiting replies from VW and Fiat regarding the allegations in the T&E report. The Times newspaper has, however, reported VW as saying that it would review the Idiada test procedures and results, while also pointing out that its TPMS systems are tested over millions of kilometres and in many different road conditions.