A flickering check engine light with a rough idle usually means an active misfire.
Here’s what to check first on your Volvo S90 II—and when to stop driving.
Why that flickering light matters
If your Volvo S90 II's check engine light is flickering rather than staying on steady, the car is telling you something urgent: the engine is likely misfiring right now. A rough idle that comes with it usually confirms that one or more cylinders are not firing cleanly. On these Drive-E engines, that can be caused by ignition, fuel, or air-metering problems—and if you ignore it, unburned fuel can overheat and damage the catalytic converter.
