An intermittent flickering check engine light with rough idle on a TANK 400 usually means an active misfire or idle lean condition. Scan it early, check ignition and intake leaks first, and drive gently until it is fixed.
Why a TANK 400 does this
On a TANK 400, a check engine light that flickers at idle while the engine shakes is usually the ECU reporting an active misfire or an idle lean condition. The light flickers because the misfire is bad enough for the computer to worry about the catalytic converter, even if it is not constant yet. Common culprits are worn spark plugs, a failing ignition coil, a vacuum leak, a dirty throttle body, or a leaking injector. On turbocharged direct-injection engines, intake carbon and boost/intake leaks can also make idle rough.
