800 Series SHP78CM5N: Bosch maps these codes to low house supply voltage, not a drain-pump obstruction. Reset the breaker for 30 seconds; if the code returns, stop and have a qualified electrician check incoming voltage before appliance service. First preserve the exact display, timing and operating state: a similar-looking code in another appliance category can mean something else. Cancel the cycle, isolate power, close the water valve and let the tub cool. Wear gloves near filters because hidden glass may be present; do not tilt a built-in unit. After the documented check, use the result to separate a temporary condition from a fault that needs authorised service.
Models covered
Safety first
- Cancel the cycle, isolate power, close the water valve and let the tub cool. Wear gloves near filters because hidden glass may be present; do not tilt a built-in unit.
What the symptom may indicate
Checks in the right order
- Record the evidence
Photograph or write down “E23 or E9001 incoming voltage too low” before resetting anything.
- Make the appliance safe
Cancel the cycle, isolate power, close the water valve and let the tub cool. Wear gloves near filters because hidden glass may be present; do not tilt a built-in unit.
- Apply the official user check
Reset the breaker for 30 seconds; if the code returns, stop and have a qualified electrician check incoming voltage before appliance service.
- Decide after one test
If the exact symptom clears, monitor one normal use. If it returns, preserve the code and contact the manufacturer instead of guessing a part.
Stop and get qualified help when
- Stop for active leaking, water in the base, uncontrolled filling, burning smell or a heat, motor or control code that returns after one reset.
Next step
Repair, replace a part, or arrange a diagnosis?
Use the checks and stop conditions above to choose a cautious next step. A symptom alone never proves that the appliance has failed.
Resolve it without buying anything
Complete the 4 user-accessible checks in order. If normal operation returns and no warning sign remains, no replacement is indicated.
Replace only the confirmed part
If the checks isolate a worn or blocked component, match its complete reference to the exact appliance model before ordering.
This guide does not identify a replacement part. Do not order a generic component from the symptom alone.
Arrange a diagnosis before replacing the appliance
Stop at any warning sign listed above. A qualified diagnosis should confirm that repair is unsafe, unavailable or uneconomical before an appliance replacement is considered.
Sources used
- Bosch — Bosch's official support material documents “E23 or E9001 incoming voltage too low” and the user-safe decision retained here.
- Bosch — Bosch's official model page identifies 800 Series SHP78CM5N as the exact catalog appliance covered by this family guide.
Last checked: 30 August 2026