L322 rr 04 4.4v8 engine light (orange)

Engine light come on for a few days then goes out for a few days, back and forth back and forth. Is this a fault in the ecu unit that needs clearing or something worse.The car runs fine not overheating all the power is there, but it drinking the beer money more than usual.
Any ideas would be appreciated thanks in advance..

You need to get the ecu read to find out. Maybe a dicky O2 sensor.