1158   Error: Ion gauge meter reading out of range (Shutdown -> Standby).

The vacuum pressure value from the Ion gauge is not within the range of specified values (When the instrument is changing from Shutdown mode to Standby mode).

Check the vacuum pressure (IF/BK). The following are the probable causes.

• The vent valve is not closed or the seal is incomplete.
• The cover of the vacuum chamber is not closed or the seal is incomplete.
• The power of the foreline pump is not connected or the breaker is OFF.
• The foreline pump oil level is low or the oil is dirty.
• There is a leak in the gate valve.
• The vacuum tubing has failed (the tubing is off, or a leak is caused by an incomplete seal such as a pin hole or a defective O-ring).
• There is a fault in the Pirani gauge (IF/BK) or the Connection PCA.