Possible causes

– Faulty Oxygen Air/Fuel Sensor Bank 1 Sensor 1
– Oxygen Air/Fuel Sensor Bank 1 Sensor 1 harness is open or shorted
– Oxygen Air/Fuel Sensor Bank 1 Sensor 1 circuit poor electrical connection
– Faulty EFI Relay
– Faulty Injector
– Faulty Engine Control Module (ECM)

Tech notes

There is a factory service bulletin for the following Toyota models:

2007