Hi
We have a Audi A4 with the oil pressure warning message coming on as soon as the revs go above about 2000 rpm.

We have removed sump & replaced oil pick up and replace oil pressure switch (genuine switch) Oil pressure is 4bar at idle and nearly 5bar when revs increase.

I have an Audi TT 1.8 T but different engine code. Oil pressure is the same at the A4 and the warning light stays off.

When we removed the sump on the A4 there was some broken plastic in there but couldn't see where it was from.

any ideas?

Also the switch on the A4 has 12V with ignition on and stays at 12v with engine running. I tried the switch from the TT in the A4 it has 12V ignition on and goes to ground with engine running but warning light still comes on.( the 2 switches are 1 digit different on part numbers but still say 1.2- 1.6 bar on both switches.

Many thanks in advance

Hi

Does it have 2 oil pressure switches ? Not familiar with this model but VAG have been known to use a 'idle' switch and a over 2000 rpm oil switch with a higher setting


Aidan

There's a good chance it is a shorted bonnet catch micro switch.

Had lots of these.

Disconnect to see if the symptom goes away.

Hi
Thanks for the replies.

I can only see 1 pressure switch & TPS say there is only 1 listed.

The bonnet shows open/closed correctly on the dash display so assumed switch is working ok but will double check switch to be sure.

Thanks

Sean

If the bonnet is showing open & closed correctly the switch is working. This bonnet switch issue gives you an amber oil level warning. Never seen one display a red oil pressure warning yet.

You should be able to view the oil pressure switch operation in dash panel.
Group 1 Block 3 is common - It displays oil pressure "OK" or "NOT OK".

The trigger for oil pressure warning is engine revs.
The 8E A4's will idle for a long time with no oil pressure present without issuing a red oil warning until the revs are raised, the switch should display live data as "OK" when the engine is started.

If you've checked oil pressure & it's okay, but the switch you fitted isn't changing it's status - the switch is faulty.

You say you've changed the switch for one that does change status, so it still doesn't tally that the oil pressure warning is active unless the donor switch is just triggering at the wrong pressure. EDIT: Or working in reverse as Tony states in the next post - VAG switches can be either open or closed circuit at rest, you may have swapped for a switch working the opposite way.
I'd try another correct genuine switch for what they cost & simplicity to fit.

After that, maybe look at live data next.
If theres no activity in live data, check whats happening at the switch - if it isn't switching when fired up & revved your issues at that end. If it switches but the dash isn't seeing it in live data block - pull the dash panel out & check the switch circuit for change of status between engine running & engine off - no change:- check the wiring from switch to dash, or if it does change test for a failed dash panel.

Jon.

>>>>>>>>>Also the switch on the A4 has 12V with ignition on and stays at 12v with engine running. <<<<<

So That switch is definitely faulty.

>>>>> I tried the switch from the TT in the A4 it has 12V ignition on and goes to ground with engine running but warning light still comes on.<<<<<

And The switches are different part numbers. ?? (That could ring alarm bells )

Could it simply be that One of the switches is Normally closed and goes open circuit on startup. ( Yours ) and The one from the TT is normally open and closes on startup. ?

Try Earthing the wire out, Start the car and remove the wire from earth then rev it up to see if the warning is still present.

( Possibly after checking data as John suggested which could show OK or Not OK the wrong way around )

Hope I haven't muddied the waters. Tony.