The (stock) sender is about a year old, pressure is sometimes zero at idle, sometimes
around 20. I know I need to check with another gauge, but I'm betting it's either the
sender or the gauge itself. I grounded the sender wire, key on, it stayed at zero.
Are there any other quickie checks on the electrical side I can do? All other gauges/lights are normal, engine is about two years old but only about 3500 miles on the rebuild.
Thanks!

 

I promise, I did search. Hailers, Icemark, NZvert, where art thou? lol

 

Try cleaning and reseating the connector to the sender.

 

Been there, done it. That connector is clean. If I have 12v on that wire (I do), then ground it, shouldn't the gauge peg?

 

When you ground the wire out, it should peg the needle on the dash. Sounds like you have a bad guage cluster.

 

I had your same exact problem. it turned out to be a bad gauge. I grabbed the gauge body minus the face from an s4 cluster since s5 clusters are alot harder to find and it works great now. Its just a little tricky setting the needle in the right position but eventualy i got it right.

 

Thanks. Sender is new, so I bet that's what's going on.