A surveyor lc plus pump is reporting an over range pressure at about 140 bar although the pressure limit is set at 440 bar. The pressure reading itself is acceptable ( I compared the pressure with the same column and mobile phase on another lc system; identical). The flow is a little bit low but that could be fixed using the calibration parameters. The issue is software independent, it happens under Xcalibur control and also with Chromeleon. With the last one it is easy to verify the the internal limit settings on the pump (I found 440bar).

Has anyone an idea about the origin of this behavior?