I’ve had my '09 S6 for about 1.5 years now. Shortly after I bought it (35k miles), I noticed that the passenger door lock wasn’t working on warm days, so I replaced the entire unit with a brand new part. A few weeks ago, as the weather here was warming up, I noticed that it is doing it again.
I know that electrical resistance goes up with temperature, so I had assumed that the electric actuator had gone bad. Now I’m thinking that it must be somewhere in the wiring. I have checked and cleaned the connections at the actuator and it changed nothing.
Have any of you had a similar experience? Any suggestions on what to try next?