C3878 Diagnostic Trouble Code

C3878 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 C3878 diagnostic trouble code may include:

Poor acceleration
Cherry red hot catalytic converter
Possible spark knock (detonation / pre-ignition)
Hesitation upon acceleration

Possible Causes :

Some aftermarket accessories and performance modifications
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.
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.

Repair Processes :

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. 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. 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 C3878 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 C3878.

Fortunately, C3878 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C3878 Trouble Code For Specific Cars

C3878 Caparo T1 Door Ajar Circuit Short To Ground
C3878 Chrysler Vip Exhaust Pressure Sensor Intermittent
C3878 Ford Ba Falcon License Lamp Circuit Failure
C3878 Marathon Corsaire Traction Motor Encoder circuit Failure
C3878 Lamborghini P140 Solenoid Relay # 1 Circuit Failure
C3878 Lexus Is220 TCM Power Relay Sense Circuit
C3878 Umm Alter Power Supply Sensor Circuit Short To Ground