What does the code oh mean on my new pressure cooker

This appears to be a malfunctioning switch that indicates cooker has built up pressure. So it may be a leaky lid or the pressure release valve (on top of lid) isn't seated well. It could be that the switch is dirty (perhaps from cooking overflow).

From this site http://www.fixya.com/support/t5273731-displays_e2_e4_5_qt_wolfgang_puck the fix appears to be easy.

Good Luck!

The error code E8 means the pressure protection is not working; here is the link for the manual
https://www.hippressurecooking.com/farberware-7-in-1-programmable-1st-gen-pressure-cooker-manual/
The manual does not discuss possible reasons for this. I have to assume there is some kind of issue with the pressure release valve. take a look and see if it is stuck or there is some kind of buildup in or around it preventing it from operating. There is a manufacturers help line listed and the only thing they recommend is to call it. Hope this helps.

Sounds like your rice cooker didn't recognized Inner Pot
sitting in on it,
Check handle and switch sensor on center of inside rice cooker
PS: l_ _l Meaning is NO POT !! (Its a symbol)

Technique code K6023 pressure cooker manual

Technique by Cook Essentials Digital Pressure Cooker Manual

IF you press and hold the top two buttons for 10 seconds the display will show a few numbers.. then press the bottom right button.. ours went right back to F4 and the only thing we could find mentioned is that a "sensor" was bad.. right out of the box this PC was JUNK.. awesome!

Halt, do not use this pressure cook. The lid is suspose to lock. This means the lid become a dangerous fly object if it came off under pressure, plus extremely hot boiling water and the contents of the pressure cooker. Beside possible dying from the lid, and if one survives the flying lid, one will be will scalded by the contents of the pressure cooker. Another pressure cooker manufactured in China. Sorry, GB...stewbison

I think E2 means open circuit in thermocouple in center of bottom. E4 means no contact on pressure sensing switch at edge of bottom. Mine had E4 error. Took out switch and used fine sandpaper to clean contact points. Now it works fine.
Remove 3 screws in bottom. Remove bottom cover by turning it ~1/4" to clear tabs. Remove switch at edge of bottom with two blue wires going to it. Clean contacts and replace.

Removed the 3 screws on the bottom. There is a relay near the circuit board. Kind of looks like an old morse code relay. Just tapped out "E 4" in morse code. Plugged it in and it works fine.

before using the pressure cooker make sure the bottom of the container is dry.. I got this error then i just wiped of the bottom of the inner container.. turned off the pressure cooker then turned it on again.. it worked fine after that.. no more error.

you also want to make sure, when you use the cooker you have at least 1 cup of liquid in the cooker .. the measure cup that comes with cooker