U0378 BMW Fault Code

Description:

The issue covered by the bulletin involves a power steering noise/whine or fluid leak from the power steering pump, gear or high pressure side power steering hose during extreme low outdoor temperature operation.

U0378 Code Symptoms :

There are currently two main types of cylinder deactivation used today, depending on the type of engine. U0378 code for the pushrod design which uses solenoids to alter the oil pressure delivered to the lifters. In their collapsed state, the lifters are unable to elevate their companion pushrods under the valve rocker arms, resulting in valves that cannot be actuated and remain closed.

Diagnosis And Repairing U0378

U0378 OBD2 specifically refers to the camshaft (cam) timing. In this case, if the cam timing is over-retarded, the engine light will be illluminated and the code will be set.

How to fix U0378 code ?

• Continuous oil flow to the VCT piston chamber
• Air fuel ratio (A/F) Sensor 1 Bank 1 circuit poor electrical connection
• Faulty variable valve timing (VVT)
• Camshaft Position Sensor harness is open or shorted

Gear changes are accomplished by a command from the BMW TCM to energize the clutch actuator to release the clutch; after which various actuators inside the transmission disengage the current gear, and depending on current operating conditions, engage the next higher or lower gear ratio. All of this happens much faster than a human driver could change gears, and in most applications, gear changes are as smooth and seamless as on any fully automatic transmission.