U0921 BMW Fault Code

Description:

The Transmission Fluid Pressure Switch allows the engine's control module (PCM) or Transmission Control Module (TCM) to use hydraulic fluid to engage the clutches in the transmission to allow for smoother shifting while driving. If the PCM or TCM detects an issue with the hydraulic clutch or the pressure switch, the BMW PCM or TCM will set code U0921

U0921 Code Symptoms :

While fuel economy was increased, acceleration was seriously compromised, and the loss of engine vacuum led to a dangerous loss of braking assist when the U0921 code system was in four-cylinder mode. In addition to these issues, while the company proposed a hydraulically controlled system that could be switched from within the car, the version they implemented had to be manually changed in the engine compartment using hand tools.

Diagnosis And Repairing U0921

U0921 the main thing to check is to verify the operation of the VCT solenoid. You're looking for a sticking or stuck VCt solenoid valve caused by contamination. Refer to vehicle specific repair manual to perform component tests for the VCT unit.

How to fix U0921 code ?

• Exhaust tube
• Faulty select solenoid
• Faulty select solenoid
• Ignition coils harness is open or shorted

Regardless of the design though, the purpose of all clutch actuating systems is to improve the driving experience by removing the need for manual clutch operation by the driver.

Computer-controlled clutch actuating systems work particularly well in dual clutch systems where one clutch controls gear changes of even-numbered gear ratios, and a second clutch that controls gear changes of odd-numbered ratios.