C0921 Diagnostic Trouble Code

C0921 is a kind of OBD-II Diagnostic C-Chassis 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 C0921 diagnostic trouble code may include:

Excessive exhaust leak
Hesitation upon acceleration
Malfunction Indicator Lamp (MIL) illuminated
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.

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. 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. Once located, visually inspect the connectors and wiring. Look for rubbing, scraping, bare wires, worn spots or melted plastic connectors.

Process Tips

Diagnostic trouble code C0921 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 C0921.

Fortunately, C0921 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0921 Trouble Code For Specific Cars

C0921 Mercedes-benz 38 Air Bag Passenger Pressure Switch Circuit Failure
C0921 Invicta 3-litre SCP (J1850) Invalid or Missing Data for Mirrors
C0921 Ford Courier Malfunction Indicator Lamp (MIL) Control Circuit Malfunction
C0921 Geely Bo O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
C0921 Adler Trumpf ABS Outlet Valve Coil LF Circuit Short To Ground
C0921 Toyota Avallon NVM RF HR Failure
C0921 Chevrolet Celta Driver Power Window Up Circuit Open