My oil pressure gauge has suddenly started dropping to zero after the engine has warmed up. As long as the rpm's are up the pressure is normal, but at idle it drops to zero. Anyone have an idea, other than a bad oil pump, as to what might be wrong. I replaced the sensor unit.

id confirm the sending unit is good. get a gauge, i think they're pretty cheap. why "other than a bad oil pump"?

Yes, I replaced the sending unit and the pressure still drops when it's at idle.

ok. now go get a gauge and prove it.

Is this on the Titan re-manufactured engine you just put in??

yes, but the engine is now 3 years old and has about 35,000 miles.

to VTJeep: would the old and replacement sensors both be bad? Or would a pressure gauge plugged into the same orifice as the sensors show the same pressure as the sensors?

What is the pressure at 1000 rpm? 2000 rpm?

at about 1200 and up the pressure is at about 40 psi

Your probably OK. what is your idle speed?

around 750 rpms, and at idle the gauge reads zero (0).

When pressure drops to about 7psi ECU will send gage to zero. Verify with a mechanical gage. While not ideal 3 or 4 psi at idle is enough AS long as it comes back up with rpms. I have been driving mine for over 30,000 miles with only 4 psi.

Same as my 98. Always shows 0 at idle with check gauge light. Its been running like this for the 3 years I've had it. Great pressure at startup and higher speeds.

I sure hope this is the case, I'm going to get a gauge and double check like VTJeep has suggested. Thanks for the quick replies.

First time it happened to me I freaked out. Seems common after I searched it and figured I'd surely have rod knock form the amount of 0 pressure I've seen it read out.