2005 Audi TT Question Intermmitent Oil Light

FRUSTRATEDOWNER

MEMBER
2005 AUDI TT

Engine Cooling problem
2005 Audi TT Question All Wheel Drive Manual 61000 miles

Is there anyone out there that can help with the most frustrating problem I have incurred with a car ever! The oil light on my Audi TT Quattro has begun coming on when the car is being driven yet goes off once the car is in idle. I have spent the past 3 months replacing the sump, the oil twice, the filter twice, the pick up pipe, the oil pump and the oil sensor. I have had the ECU checked and all is OK, I have had an oil pressure test carried out and all is OK though it does drop when driven. The engine has been flushed out, the bottom end stripped down and examined for any obvious defects and the light still comes on. The car drives as sweet as a nut, there are no rattles or worrying noises but despite the car being in at Audi they cannot throw light on what the fault may be. Has anyone experienced this problem? I have only had the car 3 months and now thinking of getting shut of it as its parked up in a garage as I am reluctant to drive it in case there is something worryingly wrong. If anyone can help I will gladly buy you a crate or ten of beer!Frustratedowner
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1 Reply

MHPAUTOS

MECHANIC
31,938 POSTS

Hi there,

The oil light will be an earthing switch, when pressure drops the diaphragm in the sender relaxes and cause the switch to earth out completing the circuit and turning on the light, now I am not an Audi tech, but I would be thinking that this is the same with Audi, (single wire sender is an earth switch) ergo, if the pressure is on, the switch wire is finding a different parth to earth, I would be doing a continuity test and a resistance test of the oil sender wire, I would check the loom for signs of damage caused by chafing and I would get the instrument cluster printed circuit board check for shorts, heat stress and anything else that may case this circuit to find an earth.

P.S. If this is the case and the wire is earthing, the light should still come on if you disconnect it from the sender, worth a try, this may isolate the problem to electrical at least.

Mark (mhpautos)