Q: Oil light is on car full of oil runs smooth but oil light comes on

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I just had a motor put in this vehicle because the old one started knocking. This motor sounds great runs hard but the oil light comes on and then I get low oil pressure warnings. What could this be?

My car has 120000 miles.
My car has an automatic transmission.

Hi there. When a motor is replaced, sometimes electrical sensors that relay information to the ECU have problems in communication and can cause multiple electrical problems as you’ve described. However, it’s also possible this is mechanical, caused by a faulty fuel pump or an obstruction of oil somewhere in the lubrication system. It’s probably a good idea to have a professional mechanic come to your location to complete a low oil pressure inspection to determine the source of these warning lights and recommend the right repairs.

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The oil pressure should be checked with a manual gauge and if it is within specification then replace oil pressure sending unit. Most likely its the sending unit but an oil pressure test should be done to make sure it is not an engine oil pressure issue.

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