P2421 Diagnostic Trouble Code

P2421 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 P2421 diagnostic trouble code may include:

Malfunction Indicator Lamp (MIL) illuminated
Carbon Buildup on O2 Sensor
Poor fuel economy
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.

Repair Processes :

Look for damage to the tank indicating impact that may have damaged the fuel pump or sender. 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. Pack the connector cavity with dielectric silicone compound (same stuff they use for light bulb sockets and spark plug wires) and reassemble.

Process Tips

Diagnostic trouble code P2421 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 P2421.

Fortunately, P2421 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P2421 Trouble Code For Specific Cars

P2421 Dodge Neon Ignition Run Circuit Failure
P2421 Tatra T107 Mirror Switch Assembly Circuit Failure
P2421 Rambler American Fuel Temperature Sensor B Circuit Range/Performance
P2421 Cottin-desgouttes 20 Fuel Shutoff Valve Control Circuit Low
P2421 Bmw Serie 3 Clutch Position Sensor Circuit Low Malfunction
P2421 Fiat Scudo Ii Lateral Accelerometer Sensor Circuit Open
P2421 Ginetta G34 Output Circuit Check Signal High