2006 BMW 530i low oil pressure warning on startup

[Slipperysalmon]

Hello,

Couldn’t find anyone else with this exact issue hoping one of you guys can help. I did the oil change used the recommended weight oil, fram filter changed both o rings. When I cold start I get the low oil pressure warning. It ONLY happens when I first start the motor. I turn it off then on again and it’s gone. Any ideas? Thank you

[jclausen]

Either an electrical glitch a bad oil pressure sender or some thing else’s the real way to diagnosis it would be hook up a mechanical oil pressure gauge and see what happens also did it do it before the oil change it did not I would replace the oil filter with a bmw filter or Mann filter

[sbrendtro]

Just a word to the wise... if you've recently had a serpentine belt break and it shredded, BE SURE to pull off the front crank pulley and see if it wrapped around the crank and got sucked in through the front crank seal. I recently had this happen and the car ran fine for a month before throwing low oil pressure on cold start like you described. Turning off and on again would clear the code, but had occasional Vanos solenoid codes (from the low oil pressure). Turned out there was a fist-sized rat's nest of old belt shreds in the oil pan that eventually clogged the pickup tube. Thankfully, I parked it and fixed before any real damage was done. Lots of work - a full sub-frame drop - but only gaskets required to fix. Best case, the seal is fine, just install an aftermarket crank seal plate for protection.

[jclausen]

That’s why you open your hood and look around with a flash light regularly to see what’s going on that way you can spot the oil leak before stuff happens

[JohnTee]

Interesting! I had the identical problem with the same vintage 535xi. Belt disintegrated. Hobbled to dealership without any power steering. Got there, they changed the belt quickly and said all was ok. I had read on forum about this possible problem. They assured me that entire belt had been accounted for and non was in engine. Vanos problems (replaced parts), low oil pressure on start up with iDrive warning not to drive car, Within several minutes of start of idling, warning light gone. Car drove well. Technician and service manager at Steal-ership insisted everything must be alright since Vanos codes cleared and at idle temp mechanically determined oil pressure was normal. Startup was always lumpy and worrisome in cold. Indy suggested that small fragments of belt might be in oil pan causing intermittent obstruction to area of pressure and quality of oil sensors. Tried to use strange brand of light oil pan cleaner, and suggested with very frequent oil changes and careful starts would clear itself up. It did although, lost faith in using car for long trips. One track day seemed to completely stop problem. Neither Indy nor dealer wanted to drop pan ( don't know why) but all seemed well. Now brake light on dash on constantly, brake sensor wear on iDrive. Had brakes, rotors replaced and OEM wear sensors replaced as well. Brake light on dash continues and Indy BMW tool suggests that both front and rear wear sensors still faulty (replaced and checked several times by careful Indy). He has found fault in ABS DSC ECU unit which he wants to send out to be repaired. Quoted almost $1000 to remove control module, send it out to a local electrical workshop to repair a common BMW ABS DSC ECU microcircuit fault. Seems that if the ECU is replaced with a new ECU or another the ECU must be recoded to match the recalled and retained BMW CAS or it will not function.
As well, after the module is disassembled, rendering the vehicle not drivable, there is no guarantee that the dismantled ECU can be fixed , and if so one is left without a vehicle for a week to 10 days only to find out one needs to go to square one. I noted that my p/n of the DSC ABS unit was DXC E6X 4WD 3451 6784157 , with ECU 3452 6784159. I called a local BMW salvaged parts dealer who claimed to have the same year and model of 2008 535xi with a removed functioning (so he says) guaranteed to work (?), total DSC ABS pump modulator with ECU. The problem is the BMW p/n is DXC E6X 4WD, 3451 6783366 and ECU is 3452 6783368-01. I looked up the part in the BMW parts catalogue but the only numbers ended in odd values for this model (may be wrong) . Can anyone help me with knowing whether the replacement unit will fit my car or is it for another placement, fitment. Finally, is removing and replacing the functioning but code popping present unit worth taking a chance on replacing when brake line attachments look more complicated. Appreciate the help if anyone knows if replacement will at least fit; understand will need to be coded then to match original (Will store codes of original); but that problem is for another day.
Thank you all for your advice.

[NRG]

If the yellow light turns on right at start up, stays on for a second, then goes off, not to come on again, this is a sign of of an oil level sensor typically. Get a code reader, and you should see it. If it is the red light, same symptoms, then it is the pressure sensor, again, read the codes.