Try clearing the error codes by resetting the ECU,this is done by disconnecting the battery for a minute or two,then go for a 15 minute drive, and then see if the error codes have returned.If they have, check the wiring and connectors to the sensors.If theres nothing out of the ordinary found, like broken wiring etc,then its most likely them sensors will need replacing.They do wear out like just like any other part and need replacing from time to time.Try to only use genuine holden sensors if you can.I have seen a few problems with cheaper sensors.They can end up costing you more in the long run.