Why does the engine oil light come on at idle but goes off when revving?
3 Answers
If the engine oil light comes on at idle but goes off when revving, it is most likely due to a malfunctioning oil pump. The oil light, also known as the oil pressure light, illuminates when the oil pressure is insufficient. If the oil light comes on at idle, you should promptly turn off the engine and avoid driving the car. Here is more information about the oil pump: 1. Function of the oil pump: The oil pump is driven by the crankshaft via a belt or gear. When the engine starts, the oil pump begins working. It is responsible for pumping oil from the oil pan through the oil passages to the camshaft and other components, ensuring sufficient lubrication during high-speed operation. 2. Types: There are two types of oil pumps—rotor pumps and gear pumps—which can provide approximately 300kPa of pressure at idle. If the oil pressure is too low, some components may not receive adequate lubrication, leading to increased wear.
I've been repairing cars for over a decade and often encounter this situation where the oil pressure light comes on at idle but goes away when revving. This usually indicates some oil pressure issues - at idle speed when engine RPM is low, the oil pump can't supply sufficient oil, triggering the warning light. When you step on the accelerator and RPM increases, the oil pump pressure rises accordingly and the light goes off. First check if the oil level is adequate using the dipstick - top up immediately if low. If the level is sufficient, possible causes include worn oil pump or clogged oil pickup screen, which becomes more noticeable when the engine is warm, especially in older vehicles. Another possibility is the oil being too thin, which often happens during seasonal changes. Don't delay - get to a shop soon to measure actual oil pressure with a gauge.
Last time my car did the same thing, the oil light on the dashboard suddenly came on during cold start idle, which really freaked me out. Gently stepping on the throttle made the light go off. I checked the dipstick myself and found the oil level was fine. Later, I asked around and learned it could be an issue with the oil pump or sensor. At idle, the oil pump rotates slowly, possibly causing insufficient oil supply and triggering the light. When the engine speed increases, the pressure builds up and the light goes off. However, be careful—if it's due to a clogged oil filter or air in the oil lines, prolonged operation like this could damage the engine. Now, I regularly check the oil quality, stick to scheduled maintenance, and use the appropriate oil viscosity. If you notice any issues, don’t take chances—get it checked as soon as possible for peace of mind.
