99 A6 Audi 2.8L Quattro
111K

Having intermittent oil pressure warning after driving a while (around 5miles)
Light comes on and off.

My mechanic changed Oil Pressure Sender and also Coolant Temp Sensor.
2Months back had to put on new Ignition Coils due to misfires.

Checked Oil Pressure and seems good (drove around 60miles after warning started coming changing sensors so its not a real pressure issue)

What could we check??

Oil Filter we ruled out as it will be giving warning all the time not intermittently.

Please advise what could I check?? Last oil change was 3000miles back.

Can I keep driving car like with beeps around this weekend??


***************11/19/2011
Issue resolved after changing Oil Pressure Sender with Audi OEM part, $20 from dealer

Per Audi specs at 1800RPM pressure has to be between 17-23 psi and pressure sender opens
the one which was isntalled was not OEM but from NAPA which doesn't open untill 25PSI where it should close between 17-25, the one from Audi closes when pressure is 20PSI, thus sending wrong signal to instrument cluster.

My mechanic (Audi enthu) was doing this test by supplying air pressure valve to the switch and figured it out and saved me without changing any costly parts ;-)

Kudos to him

 

It sounds like you have a wiring issue, either an internal break or a short to ground, intermittent of course, so you can't find it. I would replace the oil pressure sending unit with a mechanical unit and watch the gauge on my own. Either that, or replace the wire for the oil pressure sending unit to the ECU.

Good luck,

Bob

 

I will check wiring today.. what would be my next course of action if it didn't get resolved??

Just to prepare myself foe the job :-)

 

I shopped around for the connector/ wire to get it changed but couldn't find online.. Could you please give me any ref how it looks and where can I find it?

 

I go to the dealer's body shop and order it out of their specialty parts catalog. But, verify that that's the problem first by running some sort of test connection.

Bob

 

How often do you change oil? With what brand? I maybe sludge.

 

Previously using Synthethic oil 5W30. There was oil leak last year and did all gaskets and cam plugs after that my mechanic suggested to go for MaxLife instead of fully synthethic as car has morethan 100K

I have put almost 8K miles after started using MaxLife 5W30(Semi synthethic), doing oil change after every 5K Miles.. Oil sludge is very rare on this engine, oil sludge problem was on 1.8T but not suspecting this as of now as issue is intermittent not consistent.

This weekend I had driven almost 25miles on highway without any warning but got warning within 5miles of city driving in the evening :-(

hxgaser, after changing connecters I would start suspecting oil sludge.. its a very big job though.

 

MaxLife is "formulated" for vehicles over 75,000 miles, yes, but it's just another conventional oil that supposedly has extra anti-wear additives. If most of your daily driving is reflected by "city" driving, then probably pushing 5000 miles with a conventional oil is not a very bright idea. You don't drive a Toyota...and your mechanic just receives money from you...

If you check TSB 17 08-01 from Jan 22, 2008 on oils that meet Audi oil quality standards 502 00 and 505 01, then you'll find that the only "approved" Valvoline products are:
- Valvoline SynPower MXL - 5w-30
- Valvoline DuraBlend MXL - 5w-40 (this one is just syn BLEND)
- Valvoline SynPower MST - 5w-30

 

Connecters checked with meter and passed the test, my mechanic spent almost 2hrs to debug the issue.

Checked it has correct Oil Filter
Checked all Connecters
Oil Pressure sensor changed
Coolant Sensor changed
Pressure test with manual guage passed with recommended pressure
Checked all oil lines.
It can't be Oil Pump as oil pressure warning is intermittent.

Now my mechanic is thinking it could be electronics in Instrument Cluster as evrything else is checked and passed.

Do you think moving back to Audi specified engine oil synthetic will solve this issue?? is it something worth trying?? it current have Valvoline MaxLife.

Is it instrument cluster or maybe something else need to be checked??

Who can test instrument cluster??

 

An oil change isn't going to solve your problem.

Find the engine ground and clean it and make sure it is secure. The oil pressure gauge acts as a variable resistor to ground and an intermittent ground, like you would get with a loose ground wire, can cause your issue. The same goes for the display.

Good luck,

Bob