A flickering check engine light with a rough idle on your Lincoln Navigator IV usually points to an active misfire. Here’s what to check first and when to stop driving.
What a Flickering CEL and Rough Idle Mean
On your Lincoln Navigator IV, that flickering check engine light is the PCM telling you it is seeing a misfire—sometimes random, sometimes on a specific cylinder. A rough idle is the feel of that misfire at low rpm. Unlike a steady CEL, a flashing or flickering light is often considered an active, catalyst-damaging misfire. Raw fuel is being dumped into the exhaust, and the catalytic converters can overheat and fail quickly. This is not a wait-and-see situation.
