Ed with this system its either a bad wire connection at the sender or the 14 pin connector area
OR the sender has taken a dump.

Last is the gauge to have problems,
since its been working, that rules out the gauge.

 

Thanks Stan. I'm thinking the sender. How hard is it to swap it out? Do I have to drop the alternator?

 

Ed, - sender replacement:

I've done it twice on previous S4's, and it seems, as of the last drive, that I now need to do it on a GTS. IF memory serves me right, with a cold engine, disconnect the two wires, drop the oil filter (catch and save the oil in a clean container - probably less than a cup of it), then it's best to hold the 'nut' above the sender, and unscrew the sender. Reverse procedure after installing the new sender (be sure to install the sealing ring, and word is do not use the cheap URO senders). You can discard, or re-install/replace any oil. Should be a 30-45 minute job on a lift. Might be easier if you remove the left front wheel if doing it on a jack stand.

Gary

 

thanks Gary. I was hoping that was the answer, it looks like plenty of room without having to start removing externals like an alternator (which is always a huge PIA job under the liftbars)

 

its also easier if you get a few crows foot wrenches a 27 and 24 IIRC,
one to hold the mounting plate and the other to spin the sender free,
then you dont have to remove anything except the wires.
Amazon sells the crows foot tools.