Technology designed to improve diesel engine exhaust emissions has left thousands of motorists with bills of around €1,000 each, leading consumer group UFC Que Choisir reports.
The system uses a solution of distilled water and urea, branded AdBlue.
You can top up at blue pumps in certain service stations or buy AdBlue in containers from motoring shops.
It is automatically injected into a car’s exhaust system, where it breaks down polluting nitrogen oxide so that only nitrogen and water vapour are emitted.
The first indication that a refill is needed comes from a warning light and usually it takes two years of driving for this to show.
Problems reportedly come when the sensor built into the reservoir does not work.
If the fluid runs out, the car will not start until the whole reservoir is replaced, costing more than €1,000.
The sensor is not available individually.
After asking for member experiences, UFC Que Choisir collected 1,418 individual reports.
It found that Peugeot and Citroën cars were the most affected, but almost all diesel cars made between 2013 and 2020 were involved, especially those made from 2015 to 2019.
“The problems are treated case by case by manufacturers, which is regrettable,” said UFC.
“There is a lack of transparency over how much the owners will be left out of pocket.”
Only 9% of the UFC members had repairs entirely covered: 55% had a partial refund and 36% had to pay in full.
Among those who had to pay part of the bill, the average was €921.
Crystallisation of the AdBlue was sometimes found to have caused sensor malfunctions and other issues.
Risk can be reduced by not fully filling the reservoir, not continuing filling after the pump’s first cut-off, and adding anti-crystallisation agents.