Hello. My A4 2006 2T engine light come on, went to mechanic and error 0665 came on, he changed O2 sensor and reset the computer. After 30 km driving the light is back on. Mechaniv thinks it could be N75 Turbo boost sensor. Any ideas?

Thanks

 

Not a really good technician if he "thinks" rather than "knows". Did he scan it with an actualy Vag-Com? Real technicians find the source of the problem prior to simply guessing and replacing parts. Anyhow, code "0665" means numerous things. You can test your N75 by removing it.