C0406 Diagnostic Trouble Code

C0406 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 C0406 diagnostic trouble code may include:

Fuel pressure too low
Rich or lean exhaust
Diminished fuel efficiency
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

Possible Causes :

Defective ECU strategies or components will prevent proper regeneration
The Mass Airflow sensor is a hot wire that senses the volume of air entering the intake manifold. The computer uses this information to control fuel mixture.
Faulty IMRC actuator/sensor

Repair Processes :

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. 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.

Process Tips

Diagnostic trouble code C0406 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 C0406.

Fortunately, C0406 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0406 Trouble Code For Specific Cars

C0406 Chevrolet Monte Carlo EGI Temperature Sensor Failure
C0406 Ford Thunderbird Mirror Passenger Vertical Switch Circuit Short To Ground
C0406 Volvo S40
C0406 Zender Escape SCP (J1850) Lack of Acknowledgment for Audible Warnings
C0406 Oldsmobile Cutlass Cylinder 8 Injector Circuit High
C0406 Alvis Te Air Suspension Disable Switch Circuit Short To Ground
C0406 Oldsmobile Six Damper LF Circuit Short To Battery