B0921 Diagnostic Trouble Code

B0921 is a kind of OBD-II Diagnostic B-Body 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 B0921 diagnostic trouble code may include:

The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Faulty PCM
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
Engine surge

Possible Causes :

Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
An air leak forward of the DPF will change the sensor readings resulting in the code

Repair Processes :

Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. You might continue by connecting the scanner to the vehicle diagnostic connector and retrieving all stored codes and freeze frame data. If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition.

Process Tips

Diagnostic trouble code B0921 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 B0921.

Fortunately, B0921 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

B0921 Trouble Code For Specific Cars

B0921 Paramount 1.5-litre Driver Side Crash Sensor Communication Fault (Non SCP)
B0921 Mazda Millenia Turbocharger Boost Sensor B Circuit Malfunction
B0921 Mg Td All Doors Unlock Relay Circuit Failure
B0921 Mg Yb Ambient Air Temperature Sensor Circuit Low
B0921 Alfa Romeo Long Air Bag Crash Sensor #1 Feed/Return Circuit Short To Ground
B0921 Isuzu I-350
B0921 Dodge Colt Ignition Coil D Primary/Secondary Circuit Malfunction