E001 on a Viessmann Vitocal 100-A: High pressure alarm (blocks: Machine)
Short answer
On a Viessmann heat pump, E001 means: High pressure alarm (blocks: Machine). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: High pressure alarm (blocks: Machine).
Part involved: High pressure alarm.
When it shows: If the pressure transducer on the unit detects a pressure higher than 41.5 bar the alarm is triggered. In this case the compressor is blocked immediately. The alarm is reset when the pressure drops below 32.5 bar. If the alarm triggers more than 3 times ….
Likely causes:
- If the pressure transducer on the unit detects a pressure higher than 41.5 bar the alarm is triggered. In this case the compressor is blocked ….
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Auto-resets per s.13 when condition clears; manual reset required if triggered more than 3 times/hour.
Manual reset: Placing the controller in OFF mode resets alarms and hour counters (6167577 s.13, printed p.34); if alarms persist when switched on, contact technical assistance.
What you can check
- Note the E-code (e.g. E006) shown on the Vitocal 100-A controller display and give it to your installer.
- Per 6167577 s.13, switching the controller to OFF resets alarms; if the alarm is still present when switched back on, stop and contact your installer/Viessmann technical assistance (do not keep cycling it).
- Check the heat pump breaker/isolator in the consumer unit is ON and the outdoor unit is not blocked by leaves, debris or snow.
What the engineer will check
- Read alarm log (Hist) on controller; contact Viessmann technical assistance if alarm persists.
Who to ask for: Viessmann-trained heat pump engineer with F-gas refrigeration certification.
Certification: F-gas certificate (UK F-gas Regulations; Viessmann: refrigerant work by authorised refrigeration engineers only).
Sources
- Installation/service instructions Vitocal 100-A outdoor unit controller (6167577, 9/2020) ↗ · 6167577 VSA00001 · page 36 (PDF p.38) table 13.2; detail s.13.9 printed p.34-35 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026