P3400 OBD-II: Cylinder Deactivation System
P3400 Severity
Should you fix P3400 yourself?
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
What causes OBD-II fault code P3400?
In an effort to meet fuel and emissions standards, many manufacturers are utilizing cylinder deactivation systems. This system allows the engine's control module (PCM) to disable select cylinders when additional power is not needed from the engine, such as at idle or when cruising on the highway. If the engine's control module (PCM) determines that there is a fault in the Cylinder Deactivation System, the PCM will set code P3400.
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