Voltage display deviating

[Vronsky]

Dear All,
The voltage display on my SMG4 gauge reads 0.2V lower than the voltage reading of the same circuit with a multimeter:
what could be the cause ??
Can the SMG4 be calibrated/adjusted ?

Best regards,
V.

[Moonlighter]

SMG4 cannot be calibrated/adjusted.

0.2v variance between meters measuring at different points is not unexpected. Eg I think that SMG4 may be reporting alternator voltage.

[Vronsky]

Voltages are measured with engine off, so battery status only.
0.2V equals 20% charge level, so not an insignificant devation