Pressure warning Light on low revs only when moving

[chris feather]

Guys need your help !!

Ive got a 2008 A6 2.0 tfsi s line have the dreaded oil pressure light coming on very intermittently so I have flushed engine cleaned out sump cleared the strainer/oil pickup didn't find much crap all seemed ok
Ran car for a week or so no issues then its started again only when i slow down and let the revs fall below 1000rpm not every time but under heavy breaking quick beep flashes oil pressure warning then all is fine again can drive for hours no light unless i stop or slow down 

Doesn't happen on the drive when i sit and rev the car no issues at all only when the car is moving ??
Ive had it to my local garage ( A friend so no charge) who couldn't find anything wrong light never came on at all on road test so he told me to take it back and maybe change the oil sensor and if it still does it he will do a pressure test 

Ive replaced the sensor topped up the oil still the !Removed! light flashed beep goes off when revs drop under 1000 rpm but again intermittently and again never stays on

If i get the pressure checked i can't see it detecting anything because it only happens when the cars moving never when the car is stationary

Car runs absolutely perfect no rattles or engine noise at all 

Please Please any help would be great its driving mad !!!
 

[Magnet]

Hello Chris,

I notice your mechanic friend is now suggesting that this needs connecting to an oil pressure gauge to actually measure the pressure.

To me, this would have been the first port of call, since sensors and associated wiring can give spurious warnings even when the pressure is correct. As you probably know, true oil pressure should only be checked after a run of about 10 miles - when the oil is up to operating temperature. Some, incorrectly assume, that when the coolant is up to temperature, the true operating oil pressure will be achieved. Wherever possible, a car should be test driven over 10 miles to check is if oil pressure light does flick on on idle.

I am unsure whether your sitting on the drive testing is after such a run, and if so, it might point to a connection problem where car movement influences the connection. Anyway,  an oil pressure test it needs. 

Kind regards,

Gareth.

[chris feather]

Thanks Gareth I took for a good run but again only faults when moving or coming to a stop ??

aways when revs drop below 1000rpm 

Im going to check pressure from the oil sensor hole now I know where it is after fitting new one 

Do you know what normal operating pressures should be ?? or can anyone help ??

again many thanks 

[Magnet]

Hello Chris,

What grade of oil are you running the car on, and as a matter of interest, what brand. 

Oil pressures with oil at operating temperature? Temperature important as I say. 

As a rule of thumb, I would have thought not less than 40psi at 2500rpm and above, and hopefully not much less than 20psi at idle.

Others more knowledgeable on this particular engine may suggest other figures. 

Interesting to know what figures you get Chris and what the oil is.

Kind regards,

Gareth.

[chris feather]

Castrol edge 5w-30 

[Danygeorge]

Check your oil pump

 

[Danygeorge]

And don't drive your car like that....you will brake your turbo and after that your engine

[AndreiSas]

I got the same issue for over 2 years now. Done all the bits you did. Did you solved it? Thanks

[Stevey Y]

56 minutes ago, AndreiSas said:

I got the same issue for over 2 years now. Done all the bits you did. Did you solved it? Thanks

Hi change the oil pump its wear on the driven shaft.

Steve.