Started my XJ this morning on my way to work and my "check guages" light was on.. Oil pressure gauge read nothing. I pulled over checked oil, it was good. Got back in and the gauge jumped up to 45 PSI and light went away. Got on the road to work and noticed that the gauge was jumping from 12 PSI or so to 45 or so PSI. Back and forth, back and forth. By the time I got to the shop it had stopped jumping back and forth and was working as it normally does and within specs at idle and under acceleration.

Anybody else seen this happen?

 

Have you replaced it at any time? I got a new one once from an auto shop and ive read they are frequently finicky. Mine jumps around all the time. As long as the oil is good you should be alright. Make sure you dont have any serious leaks of course.

 

I haven't personally changed it. I just got the XJ a few months ago and have been chasing down quirks since. This is the first time it has happened so I am hoping that it is maybe some fluke and will be normal when I head home tonight.

The sending unit is definitely not OEM. It is a lot newer looking than 17 years old. I am not super worried that I don't have ANY oil pressure. No leaks, and oil level is perfect. It is running smooth as ever and has been getting better week by week (installed new head, lifters, water pump, etc. when I got it). More wanting to fix a potential gremlin.

I guess if it continues I'll check it with an mechanical gauge and see where my pressure is and assess from there.

 

Probably a bad sender. It's not uncommon. Mine was doing that a while ago. I bought a Bosch dash-mount mechanical gauge, hooked it up temporarily (not installed inside the cab, just connected to the oil pressure port), and it showed I had excellent pressure. Took it out, put the sender back in, and it went to showing normal pressure. It's been fine since. I'll probably put in a new sender this weekend.

The Bosch gauge cost me 17 bucks at Advance Auto. The installation, test, and putting things back to normal took maybe 10 minutes.

 

Good to know. I have seen that its not an uncommon thing for the senders to go bad. If it persists I will swap it out. In the meantime, I have an extra 3 gauge mechanical set from a hot rod I use to have that I'll verify the oil pressure is good.