Digging through code to find bugs and hidden software programs is a tough and lengthy process - just ask the Volkswagen Golf's engineers if you have any doubts - but the German Transport Ministry has just wrapped up its thorough look into the software behind one of Audi's diesel V6 engines and found something troubling. Namely, that Audi is still cheating on emissions tests by using software that can detect when a vehicle is being tested and alter engine operation so it emits pollutants at lower levels than it does when on the road.

The engine in question, reports Autocar, is Audi's turbocharged 3.0-liter diesel V6, which has been used in the A4, Q7, A6, and A8 as well as on Volkswagen models like the Phaeton and Touareg and even on the Porsche Cayenne. The real kicker is that Volkswagen has employed these defeat devices up until 2018, more than two years after Volkswagen was found guilty of widespread use of such devices during the "Dieselgate" scandal.

Germany's transport ministry is forcing Audi to recall affected vehicles within the country, of which there may be 200,000, to remove the illegal software. This echos similar recalls recently initiated by the German government, including one it forced Mercedes to issue for the diesel GLK. The difference this time, as German news outlets Bayerischen Rundfunk and Handelsblatt point out, is that Audi's cheating engine doesn't just have one defeat device...or two, or even three. Instead, it features four separate software programs that help the vehicle detect when it's on the road or when it's undergoing a test and alter the engine's operation accordingly.

Interestingly, the German government only deemed one of those defeat devices illegal, meaning that Audi can voluntarily remove the other three only if it wants to. Given that the illegal device outlined by the German authorities is part of the engine's warm-up software, we can assume that the other three devices each pertain to other engine functions.

One question that's left to be answered, however, is in regards to why the government is letting Audi off so easily, only forcing it to remove one of four defeat devices and not imposing a large fine on the company in the style of Dieselgate. That has to do with the obscurity of the law surrounding defeat devices. That's because regulators do let automakers to install software that allows the engine to emit more pollutants than the rules allow, but only as long as it's to protect the engine in stressful situations, such as when being started up while cold.

The problem is that the line between a piece of engine-preserving code and full-fledged defeat device is pretty obscure, meaning we get situations like this where regulators have to go through code on a line-by-line basis (in this case, the code was supplied by a self-implicating Audi) as well as determine if the device is an attempt to illegally cheat emissions regulations or not. Expect to see more cases like this in the future.