Pegged Oil Pressure

Two days ago I was cruising down the highway in the '01 XJ when I saw that the oil pressure needle was pegged at the top side of 80psi. I pulled over, let it idle for a few seconds, didn't notice anything different about the engine, then killed it and checked the oil level to see if anything was unusual. Nothing out of the ordinary so I assumed it was the pressure sensor that was bad.

Two days later I changed out the oil and filter as it was due and I'm taking a hefty road trip this weekend. Nothing unusual in the oil color, no sludge, and the filter seemed fine too. After the oil change it was doing the same thing - sitting on the high side of 80psi.

Is this indicative of a bad oil pressure sensor? Nothing on the FSM shows you how to troubleshoot high pressure, just low pressure. I picked up a new sensor this afternoon for $41 at our local parts store but am looking for some solid support before I throw the parts towards it. My store is good to me and will let me return it if it's unused.

Any ideas? Bad sensor?

To be sure of your pressure, I'd get, borrow, rent a mechanical gauge and take a reading. That will let you know for sure if your gauge, sending unit, or ?? is faulty.

You didn't say what year model. I cant remember but the Renix and HO give a different reading when the gauge is bad/disconnected. One shows 0 psi the other pegs the meter.

RENIX pegs out, past 80 psi if sender is bad or disconnected etc.

I have no experience with the HO type.

Your profile says '87 XJ, so you likely have a bad or disconnected sender or gauge. On my '91 HO, the sender is right next to the oil filter ... I'm not sure about the location on the 84-90 Renix systems, but it's probably in the same place. Are you sure your sender is plugged in properly? You should see a wire going to it.

87-90 :greensmok

OP says 01 xj. ???

My 99 pegged out and it was the sending unit.

To test the gauge: Hold the trip odometer reset button in, then turn the key to On, then release the button. The gauge will go through the self test routine. Pretty easy, just watch for movement.

To test the actual pressure, use something like this:
http://www.harborfreight.com/engine-oil-pressure-test-kit-98949.html

I'd wager the sender has failed; not terribly uncommon for them to do so. Scroll to the bottom of the page for related threads if you're so inclined.

muddypunk said:

87-90 :greensmok

Click to expand...

91to99 said:

OP says 01 xj. ???

Click to expand...

Whoops ... LOL.

But still ... the first thing I'd check is the wire at the sender.

Yeah, like the original post says, this on my '01 XJ Sport. I tried the gauge self test already and all the gauges and lights work as advertised - meaning, the needle stops at the right spots while moving through the full travel of the gauge.

I think I'll just swap it out in the morning. It has 101K on it and is probably OEM anyways.

I pull the wire connector on the oil pressure sender every time I change the oil due to the fact that I use the over sized filter and need the extra room to get in there. From time to time right after an oil change my gauge will peg to the max. I pull the the wire, clean and reconnect making sure it is seated all the way.....problem solved. This is on my 93'.