Check this first
Check the air filter, intake hoses and sensor connectors before replacing anything.
What usually fixes it
In the order a good shop checks them. Typical total: $114–$925 at $130 an hour.
Sensor plug or wiring
$114–$282Connector problems mimic dead sensors.
Injector or mixture fault
$248–$925Lean, rich and injector codes usually live here.
This is the advice for this family of codes – Drive DTC doesn't have advice written for P0103 on its own yet.
Code titles are the generic SAE definitions. Prices are typical US parts and labor for a common car or light truck – a guide for judging a quote, not a quote. Always confirm a repair against the vehicle in front of you.