"One Place" false voltage reading

[Shuffster]

Recently replaced my house batteries (4- 6 volt). After a couple of days of staying at parks with hookups, I found a nice riverside park with no hook ups. Anxious to see how the new batteries would hold up, I checked the house voltage at the "One place" panel. To my suprise, the reading was only showing 12.1 volts. On a whim, I grabbed my digital volt meter and checked the 12 V. power outlet by the dining table and also in the bedroom. Voltage showed about 12.6 convincing me that the One Place reading is off. Question- what's the best way to correct the One Place reading?

[NoMoreAZ]

What does your OnePlace meter read in the 'Engine' position. S/B 13.3 +/- VDC. What was the 'House' reading while on shore power? Are all the sensor wires reinstalled on the house bank correctly?

[Shuffster]

The chassis battery reading somewhat followed the house reading. I should point out that this false reading is intermitent, occassionally right, but mostly wrong.

At battery connections, no sensor wires, just the big cables, which I checked for being secure. I guess I will open up the One place panel and look for poor connections, perhaps a ground.