P258B Diagnostic Trouble Code

P258B 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 P258B diagnostic trouble code may include:

Diminished fuel efficiency
Fuel pressure too high
Malfunction Indicator Lamp (MIL) illuminated
Hesitation upon acceleration

Possible Causes :

A plugged converter will cause of host of driveability problems as well as set this code. A severely plugged converter will result in the inability to increase rpm when under load. Look for a code such as P0421 -- catalytic converter efficiency below threshold if the converter indicating a faulty converter.
Dirty air cleaner element Damaged DPF
Faulty IMRC actuator/sensor

Repair Processes :

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. 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. Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness.

Process Tips

Diagnostic trouble code P258B 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 P258B.

Fortunately, P258B is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P258B Trouble Code For Specific Cars

P258B Fiat 505 Lamp Backup Switch Input Circuit Failure
P258B Fairthorpe Electron Injector Circuit Malfunction - Cylinder 3
P258B Cadillac Srx Dim Panel Potentiometer Switch Circuit Failure
P258B Martin Aero Transmission 4-Wheel Drive Mode Select Open Circuit
P258B Steyr 220 Lamp Seat Belt Circuit Open
P258B Hotchkiss Anjou Ride Control LF Shock Actuator Circuit Short To Ground
P258B Frazer Six NVM RF HR Failure