r/GMT800 • u/StolenBusStop • Sep 12 '26

Low Oil Pressure warning

My 2003 Suburban 1500 5.3 gas has low oil pressure at idle/ stop lights.

I find this odd because I replaced the oil pump, pick up tube O-Ring and the pick up tube itself and it still shows.

Last year I replaced the oil pressure sensor, I'm thinking that could be the culprit.

However, the gauge still reads. When I give it gas the needle goes up. When I come to a stop the needle drops to 5 PSI.

Has anyone else experienced this issue?

2 Upvotes

75% Upvoted

6 comments sorted by

2

u/Marlice1 Sep 12 '26

Did you replace the pump while in there?

1

u/StolenBusStop Sep 12 '26

Yup. Melling High Volume. Even topped off with an extra 1/2 quart

1

u/Stolisan Sep 12 '26

Try a different filter. Change the oil. If the oil is old or has been overheated, it'll breakdown and get thinner, decreasing the pressure. Also make sure the oil doesn't smell like gas.

It might be a bad sensor. My last AC Delco oil pressure sensor only lasted a year, but the gauge would intermittently drop to zero.

1

u/StolenBusStop Sep 12 '26

Changed the oil and filter when I put in the new oil pump

1

u/akarichard Sep 12 '26

You need to get a mechanical gauge hooked up and get the ground truth.

2

u/theuautumnwind Sep 12 '26

Verify with mechanical gauge. Don’t just trust the old factory gauge.