P1123 Chevrolet Long Term Fuel Trim Adjustment Bank 1 System Too Rich

Possible causes

– Faulty HO2S
– Faulty Mass Air Flow Sensor
– High fuel pressure
– Canister purge solenoid stuck open
– HO2S harness is open or shorted
– HO2S circuit poor electrical connection

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)