C0104 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 of a C0104 diagnostic trouble code may include:
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
Reduction in engine performance, especially at low RPM levels
Possible Causes :
A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
Some aftermarket accessories and performance modifications
An air leak forward of the DPF will change the sensor readings resulting in the code
Repair Processes :
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.
Now, clear the codes and test-drive the vehicle to see if the code is reset.
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.
Diagnostic trouble code C0104 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 C0104.
Fortunately, C0104 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.