2011 Audi A4 B8 low oil pressure switch off engine message

[Alimosh]

Can I please get assistance. I have done engine overall on my 1.8 TFSI. Replaced turbo, PCV, oil pump, two (brown and blue) pressure sensors. I am getting the message "low oil pressure switch off the engine" at low revs up to 1600.

[Kolbenringe]

Can I please get assistance. I have done engine overall on my 1.8 TFSI. Replaced turbo, PCV, oil pump, two (brown and blue) pressure sensors. I am getting the message "low oil pressure switch off the engine" at low revs up to 1600.

Manually check oil pressure with a guage.

I remember there was another similar thread last year.

[Alimosh]

Pressure was checked manually and it is fine

[Kolbenringe]

Did you reverse the switches? Do you have the old ones to reinstall?

[Alimosh]

I will reverse them, and reinstall the old ones. The frequency is higher with the new ones, the frequency increased after installing the brown one (next to the filter). With the old ones it could go a day without error message.

[Smac770]

"and is fine" is not numerical data.

The workshop manual has specific values and test points for checking the oil pressure. What is the measured oil pressure at idle, 2000rpm, and 4000rpm (manual says 3700, but 4000 is easier to see; 3500 is the oil pump switchover point). Oil must be at least 80°C. Should be at least 1.2 bar at idle, 1.6 bar at 2k, and 3.0 bar at 3700.

The switches are just toggles, open until enough oil pressure exists to close it. Brown (F378) will trip somewhere between 0.55 and 0.85 bar, confirms minimal oil pressure. Blue (F22) will trip somewhere between 2.15 and 2.95 bar, confirms high pressure mode.

There's no reversing the switches, the brown goes where the brown goes, the blue goes where the blue goes, each plug goes where it belongs.

Is yours the design where the blue is down next to the accessory belt tensioner, or the design with it right below the brown on the oil filter bracket? Brown is closest to the filter in either case.

Wow, wiring diagram says they used the same wire color for both sensors on the 1.8T. What a bunch of idiots. white/gray. But there's also a footnote that the wire to the F22 (blue) might differ. You could confirm which one is connected to pin 9 on plug T17r (white one in the ECM box), that's the one that goes to blue.

If it were inverted, you should see that in the measuring values for the oil switch status. Correct would be 1 (low) or 3 (low and high). Inverted would be 2 (high only) while oil control valve switch was 0 (deactivated, high mode).

[Alimosh]

My blue one is next to belt tensioner.

[Alimosh]

I put back the old brown switch (one next to the filter). the frequency dropped significantly, bip message only comes when I parked the vehicle, and not all the time when I park, at least twice when I park there was no bip message for low oil pressure. Also what I noticed between the new and old brown switches, the new switch had slightly bigger opening (not as big as the blue switch though) as compared to the older one.

[Kolbenringe]

I put back the old brown switch (one next to the filter). the frequency dropped significantly, bip message only comes when I parked the vehicle, and not all the time when I park, at least twice when I park there was no bip message for low oil pressure. Also what I noticed between the new and old brown switches, the new switch had slightly bigger opening (not as big as the blue switch though) as compared to the older one.

Again, when hooking up a pressure gauge, what numbers are you getting and where in the rpm range?

[Alimosh]

Oil at 90 deg.C; 1.35bar at idle, 1.8 at 2000 and 3.3 at 3600.

[Smac770]

You'll need to log the engine speed, oil temp, coolant temp, activation of oil pressure switch valve, and status of oil pressure switches and see what's actually occurring. Below 3500rpm, the switch valve should be activated (1), invoking low pressure mode. The pressure switches status should be 1 (binary - high 0, low 1) during this time. Above 3500rpm and during other particular events (cold start high idle, etc), the switch valve should be deactivated (0), invoking high pressure mode. The pressure switches status should be 3 (binary - high 1, low 1). All the ECM knows is those three values, is the N428 activated (command), is the F22 activated (response), is the F378 activated (response). Is there an illogical state being presented, is there a lack of high pressure status when high pressure is invoked even below 3500, or is there no low pressure status present. Does this change as oil and coolant come to normal operating temp.