Oil pressure gauge reads ZERO!

[Louiej99]

Started car this morning to go to work and I get the "CHECK GAUGES - OIL PRESSURE" chime. Sure enough the gauge was at zero. The gauge cycled on power up but stayed at zero.
Yes, the car has oil. Not making any noises that would indicate no oil. I'm guessing bad oil pressure switch. Had one on the wife's car do the "full scale" thing, replaced it and was fine. Is reading ZERO a common failure mode, too.
I left it home to look at after work but how can I verify its a bad switch and the engine is actually getting oil? I can live without a gauge till I change it this weekend (have to change oil anyway). Just don't want to blow the engine up.
HELP!!!!

[J Wikoff]

You could try watching through the oil fill hole at idle to see if it looks like there is any oil movement. It won't be a gushing deluge, so look closely.

[nos4blood70]

I had one read zero for a second at random and throw that warning on the DIC screen. I'd bet it's the switch. Easy replacement, above the oil filter.

If the car had no oil pressure you'd know lol

[dougtoth]

I have had one read zero and one read 120.
When it read zero it would ding and show up on the DIC.
I also bet it is the switch.
You would hear the engine knocking or rapping if there was no oil pressure.
I bought a 27mm deep socket which makes the job easier.
I think I have changed 4 or 5 over the years.

[Louiej99]

Yeah. Ordered the new switch and picking it up after work. Was just trying to avoid an hour of cursing and swearing crawling under the car after work. Done it before. Tight fit, but haven't done it enough times to justify buying a $15 socket. I either used an adjustable wrench or my giant channelocks and slowly worked it out. New one went in a lot faster.
I agree, it would be making all kinds of sounds of it really had no oil pressure. Just don't want to take any chances.

[idensm]

I just replaced my pressure sender. I had recently replaced passenger CV shaft and the banging around apparently damaged the pressure sender. Rockauto time once again since they sold the AC Delco part. I did find a 1&1/16” socket in my tool bin thankfully. Adjustable wrench didn’t look fun on youtube videos. This failure does beg the question of the condition of your CV shafts? If they are sloppy, that sensor being so close is a likely victim? Best of luck. You are right, not likely to have no oil pressure, gear pumps don’t fail that way and the oil filter assembly has a bypass. If there were no pressure, your lifters would be clacking away fast!

[Louiej99]

Problem solved. Changed the switch and have oil pressure. Ended up using my giant pair of channel locks.

[nos4blood70]

Nice!

[Jazzy]

Same issue now on my 2000; started a week ago after hitting high water level, made worse by splash from big SUV. Pulled over and checked oil level, good, and motor sounded fine. An hour later gauge started working intermittently, but now does not work at all. I had replaced oil pressure sending unit with new AC Delco 10 months ago. Yesterday, I took off connector to sending unit and sprayed electronics cleaner and gobbed dielectric grease on connector and on sending unit. Wires from connector looked good. Still gauge is at zero (after first moving to top for moment when key is turned on). Disconnected battery for 30 minutes hoping for reset. No change.

(By the way, found the bolt holding negative cable to side-terminal battery was mostly stripped and only half way in battery since some store replaced battery a year ago; I replaced bolt (NAPA short) and tightened all the way down. Don't know how the car was running good before with such a partial ground)

Question: Did the water short the newish sending unit, or the connector wiring? Ordered a new connector, but looks like a real pain to splice it in, very limited room to work on wiring there? Anyone with similar experience and advice? Thanks.

[nos4blood70]

I would just grab another sensor and toss it in at the next oil change, I've replaced this part like 4 times now during my time with the car.

[Jazzy]

Thanks for your advice. Were you using the AC Delco sending units? That's what I was thinking of doing first before getting into redoing the wiring connector. Replacing the sensor/ sending unit was easy as I bought the special socket tool. Splicing in the new wire connector looks tough, I don't see the room there to do it right. And of course, this happened the day after I changed the oil (Valvoline full synthetic high mileage 10w-30) and AC Delco filter, so it looks like doing that again after taking off the filter again to have room to work on the oil pressure sending unit and or connector. May just do them both while I'm there. I have to see my oil pressure, you know. AC Delco OEM/GM parts are supposed to have a 2 year warranty on most parts, but I am trying to learn the details (bought on Amazon).

[dougtoth]

I replaced them 3 or 4 times now.
I went to Auto Zone which has a lifetime warranty.
I don't think it matters what the brand is because they are all made in China.

[nos4blood70]

I've tried all manner of brands, most recently went for the ACDelco. Been on the car for about 30k miles now.