B0408 Diagnostic Code And B0408 OBD-II Code Look-Up ...

B0408 Diagnostic Trouble Code B0408 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 B0408 diagnostic trouble code may include:

• Faulty or damaged wiring
• The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
• Poor fuel economy
• Rich or lean exhaust

Possible Causes : Faulty IMRC actuator relay (if equipped) A large air leak at or near the number one oxygen sensor would also cause a lean mixture. 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 :

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. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. 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.

Process Tips

Diagnostic trouble code B0408 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 B0408.

Fortunately, B0408 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

B0408 Trouble Code For Specific Cars

• B0408 Mitsubishi Pistachio Aux Heater Coolant Sensor Circuit Open
• B0408 Tata Estate Mirror Passenger Up/Down Motor Stalled
• B0408 Tatra T77 Mirror Switch Reference Voltage Negative Common Open Circuit
• B0408 Wolseley 4 SCP (J1850) Invalid or Missing Data for Steering Column
• B0408 Mercedes Sl 400 Air Bag Crash Sensor #2 Feed/Return Circuit Open
• B0408 Vauxhall Frontera Pressure Control Solenoid A Control Circuit High
• B0408 Maserati 8 Transmission Fluid Pressure Sensor/Switch B Circuit