did not use o ring, could this be the problem. engine light on
My car has 125000 miles.
My car has an automatic transmission.
Engine oil pressure may go lower after an engine gets warm. You should have the oil pressure checked with a gauge tester to verify the oil pressure is within specification. If it falls to below specification, then you should replace the pump using a high pressure pump and not an aftermarket high volume pump. While you are doing the pump check a couple main crankshaft bearings to make sure they are not damaged. If you want to have this diagnosed, the Engine Light can be scanned for codes to help pinpoint where the issue is.