What is an Engine OBDII Error Code P3400?
A Honda with an Error Code P3400 is a “Cylinder Deactivation System Bank 1“.
This error can be caused by several things but is commonly caused by a bad oil pressure sensor,
Possible Causes Engine Error Code P3400
- Defective cylinder deactivation solenoid
- An open or short in the cylinder deactivation solenoid harness
- A bad electrical connection in the cylinder deactivation solenoid circuit
- Defective mass airflow sensor
- Defective throttle position sensor
- Defective intake control manifold absolute pressure sensor
- Defective lifters
- Restricted oil passages
- Low engine oil level
- Poor oil pressure on the lifters
A P3400 Error Code in a Honda is often a bad oil pressure switch sensor.
While this is a common cause, it is not the only thing that can cause an error code P3400.
Often, the oil pressure switch sensor is replaced first since it is a common problem and low-cost part.
Example Honda Oil Pressure Switch on Amazon
Beck Arnley 201-1649 Oil Pressure Switch With Light
How To Fix Honda Engine Error Code P3400 (Replace Oil Pressure Sensor)
- Bad wiring or ECM could also cause this error code with the sensor the usual problem.
- It will have a wire plug harness that will need to come off to remove it.
- A 24mm Deep Socket will need to be used to remove it.
- Once the old sensor is removed, install the new unit making sure it seals good as to not leak oil.
Fixing a P3400 is usually easy enough and falls in the backyard mechanic DIY category.
Of course, if in doubt call a professional.
The make and model of a vehicle will make a difference as some will be easier to work on than others.