1st technical question on here. Been lurking/searching for a while. Finally need some help.

My 2000 4.0 2WD XJ was handed down to me some time ago with some issues. One of them being when I hit a bump the check gauges light come on and the fuel pressure gauge drops from 40 to 0. After another bump or two the gauge returns to normal and the light goes off.

Sounds like a loose sensor in the system. Anyone know for sure? Or where to find it/diagnose it?

Thanks for any help.

I would check the oil pressure sensor, it's near to oil filter. Either their is a loose connection or the sensor is starting to go bad.

It's the grey thing above the filter.

Thanks i'll take a look at the sensor. Image really helped out.

Good advice above. Sometimes that sending unit connector gets bumped a bit when changing the oil filter.

The fact that it changes so rapidly when hitting a bump begs of a connectivity issue.

Good luck and keep us posted!

So I received this today and put it in:
The old one had the oil pressure at 40-50 constant. After starting her up with the new OPS it went up to the usual 40-50.

Took her for a spin and after a couple minutes the gauge dropped to a constant 10. Engine still runs/sounds fine.

Faulty sensor? Any ideas? Going to test it tomorrow with a longer drive, if no change, then return.

Was it around 10 idling?
If so perfectly normal.

Constant 10. I revved it pretty high to check if that was it. no change sadly.

You coulda got a dummy light sensor and not a gauge one.

I don't know what you mean by that.

Some XJs came with gauge clusters that only had a dummy light for temp, voltage and oil pressure. The sensors for these clusters are different than the ones with gauges. How many contacts does the new sensor have?

Oh interesting... the old and new one both use the three prongs.

Then that should be a gauge one.
What brand?

replaced with:
I believe the previous was OEM.

Hmmm.
Normally our Jeeps only like Mopar sensors. Mine was from a part store when I broke it working on the transmission. Mine either is around 40-50 all the time or its ~20 at idle and 40-50 at speed.
Might wanna check wires and replace with a Mopar sensor.

i'll see how it works for a few days - might have to return it for being ****.