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  1. #1
    Active Member One Ring
    Join Date
    Jun 09 2018
    AZ Member #
    Northern CA

    Please explain in detail the oil pressure warning system in my 20 5 speed 1.8t Avant?

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    I want to replace the oil pressure sensor with an oil pressure guage from ECS tuning. The pressure sensor warning comes on anytime the car is under acceleration and rpms are between 2000 and 3000.

    At idle no warning.
    Running all rpm 3000 and up no warning light.

    Downhill foot off the accelerator in gear 2800 rpm no warning light.
    So my question to the forum is as follows:

    Is the oil pressure sensor relying on throttle position?
    Could a faulty accelerator position sensor cause the warning light to go on?
    The realtime mpg readout on the dash is spitting out some absurd numbers which has me questioning the veracity of that system.
    How do I eliminate the sensor and just rely on my own pressure guage without the annoying warning light coming on?

    Please note that I'm looking to drive the motor with 224,000 into the ground, because I already have a replacement motor and manual transmission waiting in the garage. My parts car is a 2000 1.8t manual 4 door with 135,000, I plan on swapping in the motor to the Avant. So if the motor dies its not a concern, just want the warning system disabled.
    Also I have driven about 300 miles, aggressively and the car sits dead center on the thermostat, if anything it is responding by performing better the more i drive it, all the while with the annoying warning light anytime the rpm passes through the 2000 to 3000 range.

    Thanks in advance to anyone who can expound on the intricacies of the oil pressure warning system and how to disable/bypass it.

  2. #2
    Active Member One Ring
    Join Date
    Jun 09 2018
    AZ Member #
    Northern CA

    The header is supposed to read "2000 5 speed 1.8t Avant"

  3. #3
    Veteran Member Four Rings Seerlah's Avatar
    Join Date
    Dec 05 2007
    AZ Member #
    A place between here and there
    Items for Sale

    That light is rather important, and not something to disregard. Either your sensor is faulty, wires corroded (doubtful), or you really do have low oil pressure issues. These engines are notorious for getting the oil pump pick up tube screen clogged, resulting in low oil pressure issues and damaging engines.

    Use the search function and research how to go about this properly (ie testing oil pressures at certain rpm to see if they are in spec, possibly need to drop oil pan, etc). But trying to delete the stock sensor and placing in your own in-cabin sensor is not something people try and do on these cars.
    I hate it when my car acts like a little bitch, treating me like a bitch

  4. #4
    Veteran Member Four Rings walky_talky20's Avatar
    Join Date
    Jun 30 2008
    AZ Member #
    Erie, Pennsylvania

    No. Throttle position has nothing to do with an oil pressure light. The oil pressure warning system has only 3 inputs:

    - the oil pressure switch (fairly high theshold: approximately 15psi or so). It is not a sensor. It's just a switch: open or closed.
    - engine rpm
    - coolant temperature

    Basic Rules for oil pressure warnings:
    - With engine COLD (coolant temp below 60C), oil pressure switch must stay closed at all times with engine speed over 300RPM
    - With engine WARM (coolant temp above 60C), oil pressure switch must stay closed at all times with engine speed over 1500 RPM.
    - With engine RPM at zero (key on, engine off), oil pressure switch must be open.

    Fun Fact: the oil pressure warning system is not active at all during Hot Idle. You can literally pull the drain plug out while it's idling and the engine will seize before you get any oil pressure warning. This is cost cutting. Older Audi's got 2 oil pressure switches so the system could be active all the time.

    Correct response to any oil pressure warning on a 1.8T:
    Step 1: Panic.
    Step 2: Measure the oil pressure with a mechanical gauge.
    ^Don't listen to this guy, he's not even a mechanic.
    2001 Laser Red A4 1.8TQM, 5-Speed Swapped, 4.11 Final Drive, APR 93, R8 coil packs, Labree HFC & DP, 2.5" Exhaust, ST Coilovers, 034 RSB, A8 Brakes Front & Rear, 18" RS4 Reps
    2006 Passion Red Volvo V50 T5 AWD 6MT
    "You need to know what you are doing...Its like a rainbow jungle in there." - Redline380

  5. #5
    Active Member One Ring
    Join Date
    Jun 09 2018
    AZ Member #
    Northern CA

    Thank you for the explanation of the oil pressure sensor. I have a replacement sensor which I'll install and see if the light persists.
    I know it is a warning that should be taken seriously, so I will have the oil pressure checked at various rpm. If it is showing low pressure, maybe it's time to just embark on the engine swap. Possibly clean out the gunk from oil pickup while the engine with 224,000 makes it's way into my parts car. It doesn't seem worth it to start down a gunk removal path on an engine I am planning to swap out.
    I'll post when the new oil pressure sensor has been installed.


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