B1858 Diagnostic Trouble Code

B1858 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 B1858 diagnostic trouble code may include:

Fuel pressure too high
Diminished fuel efficiency
Rich or lean exhaust
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected

Possible Causes :

Fuel with a large percentage of sulfur will clog the DPF quickly
The Mass Airflow sensor will also cause this problem. Mass Airflow circuit malfunction.
Faulty IMRC actuator relay (if equipped)

Repair Processes :

Look for damage to the tank indicating impact that may have damaged the fuel pump or sender. If all testing has passed so far yet you still have the same code, check your scan tool and see if it can open and close the IMRC valve.

Process Tips

Diagnostic trouble code B1858 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 B1858.

Fortunately, B1858 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

B1858 Trouble Code For Specific Cars

B1858 Nissan El Grand Clutch Pedal Switch B Circuit
B1858 Volkswagen Caddy 2 RESCU/VEMS Input Circuit Open
B1858 Flint 60 Left Rear Sensor Circuit Fault
B1858 Rover 20 Idle Signal Circuit Malfunction
B1858 Jaguar R Seat Driver Front Down Circuit Failure
B1858 Ferrari 246 Input shaft speed signal missing/faulted
B1858 Audi 100 Alarm Panic Input Circuit Short To Ground