Hey all. I recently did the first oil change on my new to me 05 STI. It did alright during the circulation after the change, but my low oil pressure light came on on my way home from work.

From what posts I can find, I'm guessing a piece of sludge or carbon got dislodged and jammed the pressure relief valve open. I believe that valve is on the oil pump itself? Can anyone confirm that? If it is, how easy would it be to correct? Can I replace that valve, or does it have to be the whole pump?

I'm currently in the process of installing an oil pressure gauge, so I can verify what pressure is actually there. Also, I can't think of why it would, but could this have been caused in any way by the fact that I changed it from 5W30 to 5W40 during the change?

Thanks in advance.

GD or Ido or others will have best troubleshooting approach but, don't discount the possibility of oil pick-up tube failure. Not unknown and some folks upgrade to Killer B for that reason.

First thing I checked was the pickup. It was fine, but I replaced it with a new killer bee while I was in there anyway.

Any metal evident in the pan?

GD

None. No sludge either, it was surprisingly clean.

Perhaps there's nothing wrong with the oil pump.  Could this just be a failure of the oil-pressure switch?

It's possible. I'll let you know on that once I get the gauge installed.

The switch is a membrane type on the top of the block. It uses the block as a ground and 1-wire for the indicator in the dash. (the switch is somewhere under the alternator, next to the EJ25 logo cast. 25240KA040 could be the right one)

- Check for leaks, and check oil level with the dipstick first!

- Check if that wire/connector is connected. Or pull it off and ground it with a piece of electric wire. Start and see if the light goes off

I have had these fail between 4 and 12 y of car age, the are simple to replace.

Checked all that. The oil level was perfect, no leaks. After the car was wrecked previously in it's life, and rebuilt. It had a 20,000 mile motor installed. I have a new dummy light sensor in case that is the issue, I thought the light typically flickered if the sensor went bad.

On the trip home from work when the light came on, I drove it the rest of the way home (about 8 blocks) never letting the engine go above 2000 RPM. All I heard noise wise was a faint clicking that I think was lifter click, no other noises like rod knock.

97+ engines are solid lifter so you did not hear a lifter tick.

GD

Got it all sorted out today. It was purely coincidence that the light went on after a change. The sensor was faulty. In the process of troubleshooting though, I now have a killer bee oil pickup and an oil gauge.

Sadly, the gauge is a cheap digital one so not sure how accurate it is. It says I have 20psi at warm idle and about 90psi at 4000 rpm. What are the proper pressures for this car?

On 4/3/2022 at 2:22 AM, SiriusBlack said:

Got it all sorted out today. It was purely coincidence that the light went on after a change. The sensor was faulty. In the process of troubleshooting though, I now have a killer bee oil pickup and an oil gauge.

Sadly, the gauge is a cheap digital one so not sure how accurate it is. It says I have 20psi at warm idle and about 90psi at 4000 rpm. What are the proper pressures for this car?

Oil Pressure:
98 kPa (1.0 kgf/cm2, 14 psi) or more at 800 rpm

294 kPa (3.0 kgf/cm2, 43 psi) or more at 5,000 rpm