Strange Noise On Idle/engine Light

[Altia_R34]

hey guys wondering if anyone has the same problem as i do, just recently i have changed my crank sensor (the round bit infront of ther RB) and ever since it does little pops out of my exhaust, sounds like small backfires every few seconds. I believe it could be my timing belt or something to do with timing

second is , my engine light came on last night when i was driving for roughly 10 seconds and it went off, is there a serious issue here?

anyone out there that have or have had similar problems like this that can shed some light on my issue?

cheers