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Randall C
Randall C, ASE Master Tech
Category: Cadillac
Satisfied Customers: 12728
Experience:  ASE Master Tech, 32 years exp,Cadillac 6 yrs
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My low oil pressure light come on when I stop at a light..driven

Customer Question

Why does my low oil pressure light come on when I stop at a light. While being driven it does not appear. Only started after Firestone changed my oil a month ago
Submitted: 6 years ago.
Category: Cadillac
Expert:  Randall C replied 6 years ago.
Hello, this can be caused by a few things. either the oil is very low or, the oil pump is going bad or the pickup screen in the oil pan could be blocked preventing adequate oil to be drawn through. the pickup is a fine mesh screen designed to block particals to protect oil pump and they do become blocked. Big job in either case as oil pan has to come off. Lastly, the oil pressure sender could be bad. this is the best case scenario. The only way to confirm is to have oil pressure checked with manual guage OR replace the sender and hope that is it. If not? I recommend do not drive. The lack of oil pressure at idle can/will damage the internal engine. when you increase engine speed the oil pump spins faster. Eevn if screen is blocked it can draw enough through at higher engine speeds. at idle , the oil pump spins slow. This is the time the light will come on if blocked screen or bad pump OR a bad switch could? be the problem. You never want to assume the switch is bad.
Customer: replied 6 years ago.
Understood. I had the issue briefly 8 months ago but the water pump was leaking. After having it changed the light never came back on until I got the oil changed. Guess it could have been underlying until a new filter was put on.
Expert:  Randall C replied 6 years ago.
I did forget to mention that a defective oil filter could do this as well. The water pump would have no affect. You may? want to consider relacing that filter just to confirm. the oil filter does have special check valves inside. A bad filter can easily casue the light to come on at idle