Youjoy Best-22L-B: undocumented error stops sterilization cycle
What happened
A steam sterilizer displayed fault A01, which is not listed in the available documentation — the manual only describes E-prefixed codes (E01 there means a temperature-sensor fault, temperature above 250 °C as reported in the case).
What was checked
- The engineers compared the undocumented A01 against the E01 description in the manual; the symptoms did not match a temperature fault.
- They checked the feed-water quality; cross-checking with other field engineers suggested A01 corresponds to poor water quality on this model.
- They opened the reservoir and found heavy contamination and sludge inside.
Cause
Poor feed-water quality: contamination had built up in the reservoir, and the unit signalled it as A01.
What was done
The engineers drained the water, cleaned the reservoir and refilled it — the fault cleared. Regular reservoir cleaning was recommended (for example with a wet/dry vacuum suitable for wet pick-up), as reported in the case.
Safety
Before opening the reservoir, isolate the sterilizer from the mains, let it cool down and release any residual pressure; handle the drained water as potentially contaminated, with gloves and eye protection.
Lesson: When a fault code is missing from the manual, do not force the closest documented code to fit — verify the machine's actual condition such as water quality and contamination, since the cause is often maintenance-related rather than a sensor fault.
Covered in the course: Steriliser Service — Level 2: Fault-Finding →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.