Legal Documents Show VW TDI Test Mode Damaged Cars

2015 Volkswagen Golf TDI engine (Credit: Volkswagen)

If you thought the drama surround Volkswagen’s Dieselgate scandal was over, you were wrong. Thanks to court documents, we’re learning more about the emissions cheat software and why a solution wasn’t so simple to implement.

As Jalopnik points out, filings in the fraud case for VW engineer James Robert Liang indicate that “test mode” or the setting used to trick emissions tests, actually damaged the cars. To help cut down on increasing warranty claims from damaged emissions parts, Volkswagen engineers actually worked to reduce how often TDIs ran in “test mode.”

People have asked why Volkswagen didn’t just remove the ability to switch the emissions control software to the ultra-polluting “road mode” and just keep all of the TDIs in “test mode” indefinitely. We have the answer here: the cars would experience chronic problems. Exactly what would happen isn’t quite clear, but Volkswagen knew having a bunch of failing TDIs would only make the situation worse.

This software update, which helped cars better tell when they were hooked up to emissions diagnostics hardware, was implemented in 2014. It measured the steering wheel angle to tell when the car was just being driven and not tested, which is actually a pretty clever and devious solution.