Oil Warning Symbol
 

Re: 5-10-1990 - Audi Quattro Coupe 20V - 2309 cc - 5 Cylinder - Engine No: 7 A 014151

Last few weeks, oil warning symbol has been appearing erratically for a few seconds. May or may not appear on the same daily 4 mile journey.

Engine has plenty of oil and rarely needs topping up from one year to the next - around 6,000 miles per year. Also oil pressure gauge shows good pressure - usually around max 5 bar when moving, min 2.5 bar when idling and doesn't drop when warning symbol appears.

No previous problem except a year or so ago, pressure gauge went straight to max with ignition on. Traced problem to faulty Sender which was changed and everything has been fine.

Any thoughts on where problem might be?

Thanks
Keith

Sounds like frayed wiring or a loose/dirty connector to me.
Could also be a faulty sender.

I'm having a similar thing in my UR actually, worried me initially but then calmed myself knowing that it's had a full service and tuneup in the last two months and it's not burning oil as I checked the levels!

I'm thinking it may be worth me investing in a Bentley manual as I'd like to be able to find and fix these things myself!

Oil pressure switch I'm guessing. I've got a similar problem on mine. My oil pressure switch is leaking, which is why I'm going to change it shortly and see if this solves it. Double check your switch on the bottom of the sump to see if it's leaking.

Thanks for quick replies.
I do have a Bentley Manual.
Is Pressure Switch same as Sender?
I don't understand why it may be the Sender if the Pressure Gauge always gives good and consistent readings.
Thanks
Keith

Connections are vtal in my experience. The circuit on Davey's MB quattro is from the sender unit on the left hand side of the block via a relay, which is notoriously unreliable (I have at least 3 cars which would benefit from replacements but are no longer available from Audi, and the manufacturer won't supply direct because of its contrcatual arrangements with Audi!), and then to the warning light. Best recomedation I can make is to get the connectors off the senderand clean them thoroughly with a bit of emery. Its worked for me in the past. It doesn't help that the sender is under the top hose / thermostat outlet etc and is prone to getting water on it causing corrosion in the connections.

Roger Galvin
Technical Secretary, qOC
quattro Workshop

Because there's two of them - one is pure pressure switch, another is switch and sender for gauge. For the switches - one is 0,3 bar and it turns off when activated, another is 1,8 bar and it turns on when activated.

In your case it is more likely that it's problem with connection or warning lamp relay, as mentioned earlier, because if the oil pressure usually don't drops below 2,5 bar, there would be no reason for warning light to lit up even with no 0,3 bar sender connected.

By the way - I hope your oil pressure gauge reads 0 when ignition turned on but engine is not running?

Yes gauge reads 0 before starting.

Thanks for all suggestions.

Keith

If you've got a gauge and it shows OK pressure, and if the level is OK, then it's got to be a faulty sensor, relay or wiring.

Over the years I've had numerous failed sensors - they usually fail by piddling (or squirting) oil all over your engine compartment, but I did have one once that was still mechanically intact, but indicated low pressure when the pressure was fine.

I had a sensor leak last year and replaced the sensor with a part from somewhere like G&S or ECP. Within a year the new sensor was leaking so badly that I had to add a pint every 100 miles or so. I replaced it with a genuine Audi part and will only buy Audi oil sensors from now on!

Thanks for that.
Will you please clarify if my 'sender' and your 'sensor' are the same thing?
Keith