Q: a Passat 1.8T just overhauled, cold car normal, 90km/h above the speed of more than ten kilometers after deceleration, alarm lights flash, acceleration to 1800 to 2000r/min time oil light (red light), flameout restart oil lamp, and then accelerate to 1800 ~ 2000r/min alarm light flash, 2100r/min above the extinction. I have changed the oil pump, oil and oil sensor plug, and the oil cooling system has been cleaned during the overhaul. The problem has not been solved. What is the reason for this? Answer: according to your description, I think there is something wrong with the oil sensor or control part, or there is interference signal. The lubricating system is cold and the engine oil lamp is on the alert after the hot car. Because the oil viscosity of the cold car is high, the oil pressure can still be satisfied. Once the temperature rises, the viscosity of the oil decreases and the oil pressure drops, the vehicle will report to the police. Specifically, there may be too much clearance between the crankshaft bearing bush, connecting rod bearing bush, camshaft bearing bush and so on. This situation shows that the quality of the overhaul is poor, and the oil pressure gauge can be connected to the oil sensing plug hole. 2100r/min above the alarm lights out of the problem is not very serious, when the speed rises, the oil pressure increases with the speed, the oil alarm lights out, the problem is still likely to appear noise.