P3400 - CYLINDER DEACTIVATION SYSTEM BANK 1

There are certain driving conditions in which maximum engine power is not needed. In such cases, the cylinder deactivation system or variable displacement system is used. Usually, it deactivates the corresponding cylinders and achieves fuel economy in vehicles having more than 8 cylinders.

In this system, variable valve timing solenoids are used to close the intake and exhaust valves of the deactivated cylinders. In this way, cylinder gases are trapped, and the vibration is reduced. This process allows the best operation of the cylinder. By compressing the exhaust gases, the piston is also pushed back to achieve a higher degree of overall engine balance.

The P3400 OBDII fault code is stored because in a certain situation the Powertrain Control Module (PCM) fails to operate the cylinder deactivation system. It is also stored when the cylinder deactivation system is activated unexpectedly.

• The Check Engine light turns on.
• Lower fuel efficiency.
• Engine power is reduced.
• Other cylinder deactivation DTCs are

Reasons for setting the P3400 OBD2 diagnostic code:

• The engine oil may be below the required level.
• Engine oil pressure may not be enough.
• A valve timing control solenoid could be in bad condition.
• The cylinder deactivation circuit may be shorted.

To resolve the DTC P3400 OBDII code, try to do this:

• First, consult the TSBs (Technical Service Bulletins).
• Check that the engine oil pressure and level are appropriate to get a good engine performance. If one of these values is out of the range, make the right corrections.
• Check the good condition of the electrical circuit components related to the system. If you find burned wires or corroded connectors, make the appropriate repairs or changes.
• By using a DVOM, make some voltage tests on the variable valve timing solenoids. The data obtained should match the manufacturer's specifications. Otherwise, it will be necessary a replacement.