If your vehicle is showing red oil pressure light flickers at idle, here are the most likely causes and the parts you'll need to fix each one.
The most common reason for a flickering oil light is simply not having enough oil in the crankcase due to leaks or normal consumption. At low idle speeds, the pump struggles to pick up enough oil to maintain pressure.
The sensor that triggers the dashboard light frequently fails or leaks internally, sending a false low-pressure signal when the engine is warm and idling.
Using oil that is too thin (wrong grade used during a recent oil change) or oil that is heavily degraded/fuel-diluted will lose pressure easily when hot, especially at low idle speeds.
If the engine idle drops below specification due to a dirty throttle body or failing idle air control valve, the oil pump spins too slowly to maintain adequate pressure.
A severely clogged filter or a cheap aftermarket filter with poor flow characteristics can restrict oil pressure. This often happens if oil change intervals are ignored or a defective filter was recently installed.
Engine sludge can clog the oil pump pickup screen in the oil pan, or the oil pump's internal gears may be worn out, causing it to struggle to build pressure at low RPMs.
Excessive clearance from worn internal engine bearings (main or rod bearings) allows oil pressure to bleed off faster than the pump can supply it at idle. This is a catastrophic failure usually accompanied by engine knocking.