C0178 Diagnostic Trouble Code

C0178 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 C0178 diagnostic trouble code may include:

Malfunction Indicator Lamp (MIL) illuminated
Carbon Buildup on O2 Sensor
Poor fuel economy
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
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 :

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. 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. It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem.

Process Tips

Diagnostic trouble code C0178 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 C0178.

Fortunately, C0178 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0178 Trouble Code For Specific Cars

C0178 Mercedes E 220 ABS Power Relay Coil Open Circuit
C0178 Porsche 718 Front Sounder Circuit Short to Vbatt
C0178 Triumph Gt6 Passenger's Seatbelt Tension Reducer Circuit Short to Ground
C0178 Chenard Walcker Straight-eight Door Unlock Disarm Switch Circuit Failure
C0178 Ferrari P2 KAM Voltage Too Low
C0178 Fiat Ducato Lamp Park Input Circuit Open
C0178 Nsu Tt Cylinder 12 Misfire Detected