1152   Error: Backing solenoid valve (SVBK) did not open.

When the instrument transits from Shutdown mode to Standby mode, it failed to open the backing solenoid valve (SVBK) (When the instrument is changing from Shutdown mode to Standby mode).

Check the operation of the backing solenoid valve (SVBK). The following are the probable causes.

• The backing solenoid valve connector came off.
• The backing solenoid valve is defective.
• There is a fault in the Connection PCA.
• Poor connection of Pirani gauge sensor at IF/BK valve assembly.