* In Canada, we used to only ever do tailpipe tests, meaning a defeat device wouldn't be able to fool the testing. * I think you misunderstand both the testing

* In Canada, we used to only ever do tailpipe tests, meaning a defeat device wouldn't be able to fool the testing. * I think you misunderstand both the testing and the defeat device. We do tailpipe testing here in the US, and the defeat device results in far cleaner tailpipe emissions during said tests. It's not just an OBD data-hiding thing, it actually changes the emissions. edit - clarification, we may not do tailpipe tests on diesels here, didn't occur to me that gas tests would be different than diesel.