Flashing or on steady?
Mine came on when the exhaust snapped.
Always replace coil packs two at a time 1 and 3/ 2 and 4.
I had one go and replaced then about 3 weeks later another went. They all seem to start going after you replace one...
It's emissions. If it's not a spark problem but it very hesitant and jerky on part throttle then it's probably a lambda sensor.
If you've got 2 lambdas in it, replace the upstream first, or have it plugged in to see which the ECU is complaining about.