U.S. regulator California Air Resources Board (CARB) found another defeat device in Audi vehicles, which previously went unreported.

The defeat device reportedly lowered the cars' carbon dioxide emissions when they detected they were under testing conditions.

German publication Bild am Sonntag reports [subscription] that CARB found the new defeat device software four months ago in an Audi automatic transmission. The device reportedly lowers mileage, thus causing higher CO2 emissions when the vehicle is not in the "rolling road" that official emission tests use.

The publication reportedly found a document as well, which will reportedly have an impact on the career of Axel Eiser, Volkswagen Group's powertrain, if not higher-positioned executives at the company.

The carmaker reportedly wants to reach a settlement with the U.S. Justice Department and has reportedly made progress with recent negotiations, Forbes reports. However, the recent discovery makes a deal more unlikely now, the paper notes.

At the same time, the newly discovered emissions cheat device puts Audi at odds with European tax collectors, which are typically stricter than automotive regulators.

The cheat device CARB found now, which relies on steering wheel movements to detect when the vehicle is in lab testing, has reportedly been used in "several hundred thousand" cars, both diesel and gasoline, that Audi sold worldwide.

The report further points out that the defeat device was packed into Audi engines with the AL 551 automatic transmission, which was used in Audi A6, A8, Q5 and others, until May 2016. That's a hefty eight months after the massive Volkswagen dieselgate scandal stirred waves back in September 2015.

The cheating device is reportedly disguised as a "warm-up function" and as long as it's running, the transmission remains in a low rev mode that consumes less fuel and thus makes less CO2. The fuel-saving mode only activates when the car is in testing, but it automatically deactivates otherwise. This means that in normal traffic, the warm-up function deactivates, switching the transmission to a mode that burns more fuel and, consequently, produces more CO2. This normal traffic mode kicks in once the steering wheel turns more than 15 degrees.

Long story short, Audi basically figured that the only scenario in which the steering wheel would turn less than 15 degrees would be in a lab for testing, and found a way to cheat the system to make its cars seem like they produce less CO2 than they actually do.

Should this turn out to be accurate, European tax regulators will likely have a field day with the Audi vehicles in question. It remains to be seen how things will pan out, but it doesn't sound too good for Audi and Volkswagen.