Bosch Compress A01-811 fault code
Bosch Compress heat pumps
What it means
DHW: thermal disinfection unsuccessful
The cylinder did not reach disinfection temperature in the allowed time. Bosch group A01-811 and A41-4051…4052 under one table.
UK models this code applies to
From the Bosch service literature we hold (Worcester Bosch user interface HPC 410 manual 6721832682 (2021/02) §8 Unit troubleshooting, Table 25) — not a scraped list.
Compress 3400i AWS 4 kW (CS3400iAWS 4 OR-S)Compress 3400i AWS 6 kW (CS3400iAWS 6 OR-S)Compress 3400i AWS 8 kW (CS3400iAWS 8 OR-S)Compress 3400i AWS 10 kW (CS3400iAWS 10 OR-S)Compress 5800i AW 4 kW (CS5800i AW 4 OR-S)Compress 5800i AW 5 kW (CS5800i AW 5 OR-S)Compress 5800i AW 7 kW (CS5800i AW 7 OR-S)Compress 7001i AW 5 kW (CS7001iAW 5 OR-S)Compress 7001i AW 7 kW (CS7001iAW 7 OR-S)Compress 7001i AW 9 kW (CS7001iAW 9 OR-S)Compress 7001i AW 13 kW (CS7001iAW 13 OR-S)Compress 7001i AW 17 kW 3-phase (CS7001iAW 17 OR-T)
Now the harder half: proving what caused it
A01-811 names a symptom, not a root cause. In the app, the same code opens a guided investigation: what to measure first, the expected values for your exact model, and an honest verdict — including “nothing in this machine is broken” when that's what the readings say.
Chase this code in the app →