P121B Code: Meaning, Causes, and Symptoms | OBD2 Codes
P121B – Cylinder Balance Test Injector Blocked
P121B Possible Symptoms
Engine Light ON (or Service Engine Soon Warning Light)
P121B Possible Causes
Faulty Fuel Injector,Fuel Injector harness is open or shorted,Fuel Injector circuit poor electrical connection
The Powertrain Control Module (PCM) monitors the Fuel Injector. The PCM sets the OBDII code when the Fuel Injector is not to factory specifications.