French authorities are investigating Renault for possible cheating on emissions tests.

Three judges will probe possible “cheating on pollution control checks … with the consequence of making the (vehicles) dangerous to the health of people and animals,” according to Le Figaro.

A preliminary investigation found that some Renault models were emitting up to 10 times the legal amounts of nitrogen oxide (NO2).

Renault said it had complied with emission rules and that its vehicles were not equipped with software designed to cheat the tests. The company suggested a “calibration error” on an anti-pollution part could have caused the problem.

France’s Environmental Minister, Ségolène Royal, established a commission to investigate the on-road emissions of 52 cars from domestic automakers including Peugeot, Citroen and Renault, as well as foreign brands such as Ford, Mercedes, Toyota and, of course, Volkswagen.

Most of the vehicles tested recorded on-road readings up to five times those reported in laboratories. Three-quarters had emissions 20 to 50 percent higher than stated on certification forms.

French authorities have asked all the automakers to explain the results, but so far Renault is the only one subject to investigation.

Meanwhile, in the US the Environmental Protection Agency (EPA) has accused Fiat Chrysler (FCA) of cheating emissions tests using defeat devices like Volkswagen did.