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Matt
Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 21973
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Oil pressure warning light came on. Oil level is ok.

Resolved Question:

Oil pressure warning light came on. Oil level is ok. Switched engine back on and now no warning light. It's a 1 series. Why would this be?
Submitted: 1 year ago.
Category: BMW
Expert:  Matt replied 1 year ago.

Hello

I'd 1st suggest measuring the actual oil pressure with separate mechanical gauge - this can be plumbed into the engine via the current pressure switch port - if you use a Tee piece you can keep the pressure switch plumbed in as well and so see if the low pressure light corresponds to a low pressure reading.

As its intermittent and you have no rumbling or rattling noises from the engine its likely to be an electrical fault so 1st check the connection to the pressure switch is bright and clean and check back along the switch wiring for any signs of damage to the insulation

As if the wire is grounded out at any point then this will also turn on the light.

if this is all OK and the oil pressure is at least 1.3Bar ( 20psi) at hot idle then replace the switch

If you do have a low pressure reading and to turn on the light it will be very low about 5psi then replace the oil pump and ensure that the pump pickup in the sump hasn't come loose or is blocked

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