P2121 Diagnostic Trouble Code

P2121 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code.

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.

Symptoms

Symptoms of a P2121 diagnostic trouble code may include:

Faulty O2 Sensor
Lack of power
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
Diminished fuel efficiency

Possible Causes :

The Mass Airflow sensor is a hot wire that senses the volume of air entering the intake manifold. The computer uses this information to control fuel mixture.
Defective ECU strategies or components will prevent proper regeneration
Fuel with a large percentage of sulfur will clog the DPF quickly

Repair Processes :

Oxygen sensors signal the engine management computer the amount of oxygen present in the exhaust, which is used in determining and controlling the fuel ratio. 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. Now, clear the codes and test-drive the vehicle to see if the code is reset.

Process Tips

Diagnostic trouble code P2121 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 P2121.

Fortunately, P2121 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P2121 Trouble Code For Specific Cars

P2121 Isuzu Aska SCP (J1850) Invalid or Missing Data for Steering / Steering Wheel
P2121 Nsu Wankel Cylinder 2 Injector Circuit High
P2121 Simca 11 Intake Manifold Runner Control (Bank 1) Stuck Open
P2121 Nissan Note Ii Control Module VSS Output "A" Malfunction
P2121 Warwick Buick SCP (J1850) Invalid or Missing Data for Memory Storage
P2121 Toyota Gt1 Oil Change Reset Button Circuit Open
P2121 Lagonda 3.5-litre Shift Solenoid D Intermittent