Blakeslee Commercial Dishwasher Error Code B5: Boiler Overheating
B5 BOILER OVERHEATING means the rinse boiler went above its allowed temperature. The manual says to contact Technical Service. Turn the machine off, keep clear of the hot boiler, and have a service technician inspect it.
High: an overheating boiler is a safety condition, so the machine must stay off until it is checked.
- Code
- B5
- Maker
- Blakeslee
- Equipment
- Dish machines
- Applies to
- D-18D / D-18V digital-control door-type
What does Blakeslee error code B5 mean?
A heater that cannot be switched off is a hazard, so the control watches the rinse boiler temperature against a ceiling. If the reading rises above that limit, it cuts the heater and shows B5 BOILER OVERHEATING. The manual's wording is rinse boiler overheating, and the action is Contact Technical Service. There are two broad families of cause. Either the heater is staying on when it should have stopped, for example because the contactor is stuck or the control is not switching it, or the boiler has run low on water so the element is no longer covered. A failed probe can also report a wrong temperature, though that is the job of B2. The alarm is the opposite of B3, which is a boiler that does not warm up. The display text is B5 BOILER OVERHEATING.
Affected models and control systems
Blakeslee D-18D / D-18V digital-control hood-type dishwasher. The manual's cover prints D-19 L and D-19 LRS and names no D-18 model, so the alarm list is read as covering this hood-type family.
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
- B5 BOILER OVERHEATING on the display
- Steam or hot smell near the machine
- Rinse water unusually hot
- Machine stops and will not restart
Possible causes
Likely causes — what usually sits behind error code B5 on this control. A technician confirms which one it is before any part is replaced.
- Heater contactor stuck closed so the element stays powered
- Boiler running short of water while the element is on
- Boiler probe reading low and letting temperature climb
- Safety thermostat or control output not cutting the heater
Safe checks before calling for service
- Turn the machine off and, if there is a wall disconnect, switch that off too.
- Keep away from the boiler and the rinse spray, which may be scalding.
- Check that the water supply is on, but do not run the machine to test it.
- Let it cool before anyone approaches it.
- Write down the display text and whether you saw steam, leaks or a burning smell.
How a technician diagnoses error code B5
- Read the alarm record and confirm B5 and whether B2 or B1 appeared first.
- With power locked out, check the heater contactor for welded contacts.
- Test the boiler probe against a reference thermometer to confirm it reads correctly.
- Verify the boiler fills and holds its level and look for leaks.
- Check the element and its safety devices, then replace the confirmed part.
- An overheated boiler holds scalding water and steam under pressure.
- A stuck contactor means line-voltage contacts that must be tested with the supply locked out.
- Deciding between a control failure and a heater failure needs measuring the circuit with a meter.
How error code B5 differs from similar codes
B5 is the high-temperature side of the same boiler. B3 reports the boiler not heating at all.
Technical reference
- Maker documentation
- Blakeslee owner support
- Edition
- COD. 3100ET_U, Ed. 06 - 09/2018
- Models / control
- D-18D / D-18V digital-control door-type
- Section
- Chapter 8.2 Alarms, table 3 (p. 39)
- 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 Blakeslee dish machine error codes
Is B5 dangerous?
The boiler is hot and may hold steam, so keep clear and let it cool before anyone approaches.
Can I reset and run it?
Do not. The cause may be a heater that cannot switch off, and running it again risks damage.
Is this the same as B2?
No. B2 is a probe failure. B5 reports actual overheating, although a bad probe can contribute.
Need help with Blakeslee error code B5?
A technician confirms the cause on site and gives you the price in writing before any work starts.