It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.
Possible Causes :
Use the DVOM to test resistance and continuity on all system circuits if actuator and sensor resistance levels are in compliance with manufacturer's specifications. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground.
Diagnostic trouble code B0121 is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.
Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before B0121.
Fortunately, B0121 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.