Meiko UPster U 400 M2 Error Code ERR 306: Maximum Tank Level Exceeded
ERR 306 on a Meiko UPster U 400 M2 means the maximum tank level was exceeded, or the tank level analysis was disrupted. Empty the machine and refill it, as the maker says. If ERR 306 comes back, close the water supply valve and call us.
High: excess water is a leak and overflow risk, and the machine stops.
- Code
- ERR 306
- Maker
- MEIKO
- Equipment
- Dish machines
- Applies to
- UPster U 400 M2
What does MEIKO error code ERR 306 mean?
The control of the UPster U 400 M2 keeps the tank water between set levels by watching a level sensing circuit. ERR 306 is the opposite of a fill failure: there is more water in the tank than the control allows, or the level reading cannot be trusted. Either way, it stops. The manual lists the causes as a fill valve that does not close fully, a drain that is not emptying, a level sensing tube that is damaged or blocked, and surges in water pressure. A fill valve that leaks through keeps feeding water even when it is told to stop, so the tank creeps above its limit. A slow drain leaves water behind from the previous cycle. The maker's operator step is to empty the machine and refill it, which can clear a one-time case. If the message returns, there may be water coming in that should not be, so closing the supply valve limits the risk of overflow. Staff see water in the tank that should not be there, and spilled water on the floor should be wiped up.
Affected models and control systems
This applies to the Meiko UPster U 400 M2 glass and dishwasher. Other Meiko models and controllers use different numbers for tank level errors.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- ERR 306 on the display
- Tank water higher than normal
- Water dripping or overflowing near the machine
- Machine refusing to continue a cycle
Possible causes
Listed in MEIKO's documentation
- Fill valve that does not close fully
- Drain that is not emptying
- Level sensing and its tubing
- Water pressure surges
Other likely causes — what usually sits behind error code ERR 306 on this control. A technician confirms which one it is before any part is replaced.
- Debris held on the fill valve seat, so it leaks through
- Level tube partly filled with condensation or detergent that reads high
- Sudden pressure rise at the supply when other equipment shuts off
Safe checks before calling for service
- Switch the machine off and let the water cool.
- Empty the machine and refill it, as the maker says.
- Close the water supply valve if water keeps coming in.
- Wipe up any spilled water so no one slips.
- ERR 306 coming back means it is time to call us. Tell us whether water kept entering with the machine off.
How a technician diagnoses error code ERR 306
- Read ERR 306 and check the tank level by eye.
- Test whether the fill valve leaks through with power off.
- Check the drain path for slow emptying.
- Inspect the level sensing tube and connections.
- Measure supply pressure for surges.
- Replace the valve or sensor only after the tests.
- A leaking fill valve can keep adding water into a cabinet that holds live 208-240 V parts.
- Testing the level sensing needs panels off and a meter.
- Tank water is hot and carries detergent.
How error code ERR 306 differs from similar codes
ERR 307 is the level sensor itself being defective, while ERR 306 is the level going over the limit.
Technical reference
- Document
- UPster U 400 M2 Original operating instructions 9760441 (update 2026-06), 9.6.1 Messages p.33-35
- Edition
- 9760441 / Valid from: 2018-02 / Update: 2026-06
- Models / control
- UPster U 400 M2
- Section
- 9.6.1 Messages: INFO table printed p. 33, ERR table pp. 34-35 (of 50)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related MEIKO dish machine error codes
Can I keep washing with ERR 306?
No. Water above the limit can overflow, and the machine stops anyway.
Will emptying clear it?
Sometimes. If the cause was a stuck valve it will come back.
Is it a drain problem?
It can be. A tank that does not empty is one of the listed causes.
Need help with MEIKO error code ERR 306?
A technician confirms the cause on site and gives you the price in writing before any work starts.