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


P121B Description


The Powertrain Control Module (PCM) monitors the Fuel Injector. The PCM sets the OBDII code when the Fuel Injector is not to factory specifications.