filippellicarl@yahoo.com

Need help my 99 xj just started this new trick with the oil pressure gauge is pegged at 80psi. I replaced the oil pressure sensor about a month ago with a mopar sensor and it was running perfect since today. Anyone ever run into this.

lawsoncl

Is it pegged with the ignition on but the engine not running? Check the wiring to the sensor. If it's broken, the gauge will peg. The wiring often gets damaged when changing the oil filter.

filippellicarl@yahoo.com

Ok so when I turn the ignition to the on position is sits at 60psi. As soon as I start the engine it runs up to 80psi and stays there.

318SixPack

That gauge reads all the way high when there is no signal from the sender. But it could actually be high pressure, outside possibility.

Easiest first. It could be an intermittent connection issue that shows up when the engine moves and shakes. Disconnect the sensor's plug to the wiring harness, clean out both sides with electrical contact cleaner (the WD-40 brand works good, so does CRC) and reconnect. Also examine the wiring for damage. If that fixed it, dielectric grease on the pins and button back up.

Next, if you don't have a mechanical pressure gauge to check pressure with, see if a local parts store has one in their loaner tool program. If you are really getting 80 PSI after start you got an internal engine problem.

If the pressure is good in reality, then that sender is probably bad already.

lawsoncl

If you have a meter, check the resistance of the sensor. It should be close to zero with the engine off.

Dave51

Mine pegged at 80, I replaced it with this for 30 bucks:


fine so far after >2 months.

jpz

When mine pegged at 80 a few years back, I replaced it with whatever NAPA had on their shelf. Problem has been fixed since.

Time to check with a mechanical gauge to verify.

lawsoncl

I always prefer to troubleshoot before firing the parts cannon. Especially since box store parts are often worse quality than the worn out oem parts they are replacing. In this case we know it's not ready right with the engine off, so I'd check the sensor with a meter first to make sure it's not a wiring or dash issue first.

RockyMtn96XJ

What is "normal" pressure at operating temp? Mine is ALWAYS at about 60...

RockyMtn96XJ

Looks like about 40....????
Maybe my sensor is on its way out. Its been at 60 since I bought it last Aug. No fluctuations either.

jpz

Mine runs around 20 at idle when up to full temp.

318SixPack

After my oil is up to operating temp, it runs around 20 psi at idle.

RockyMtn96XJ

Old thread revival.... Since I stated above that my psi sits at 60-ish, I went ahead and changed the switch. During the install I accidentally separated the plastic housing from the metal section because I'm an idiot and I decided to turn the sensor with my hand and I heard it crack.... Does anyone know if this will completely cause a sensor to go bad immediately? I'm asking because I had also changed the plug on the harness (just a butt splice with old wire and new harness wire, not complete harness from where ever it comes from.) My psi was still pegged out way past 80psi. I put the old sensor back in and its reading just ever so slightly lower than it used to now.

I have to assume my new sensor is busted since it didnt read anything ever.... Even before the plastic housing cracked.

Side note, I realized the sensor had 2 prongs, where as my harness is the single wire type.

Will a 2 prong sensor work in a single wire setup to begin with? Or is the grounding different in a 2 prong and it needs the 2 wire type harness??

Ooooor, since I put a new 2 wire harness in and just put heat shrink on the wire I didnt need, can I go ahead and ground that wire and the sensor will work (if its not broken already)

RocketMouse

I replaced mine not long ago with a good quality replacement OP sensor...and from what I've learned, is probably much more accurate than what was in there prior... at full hot idle it sits around 35-40, and under load 55-60.
Which was a bit lower than what it was reading with the old senor. I prefer accurate over pacifying with an inflated number. Either way... I'd say it's respectable oil pressure for a 22 year old Jeep. And WELL within specs of what it actually needs to run. These motors can run safely on fairly low oil pressure. That said.... I still like the fact that mine sits happily right in the mid range being as old is she is.

RockyMtn96XJ

I'd feel better if my pressure fluctuated at all. but it seems to sit right at the 60psi mark. Hot, cold, idle, 2000 RPMs.... it only moves just a hair if I really have to give it some gas.....