Verified boiler fault code
Alpha 05 Fault Code (Evoke 28 and 33)
CH flow sensor fault.
Safety disclaimer
Fault code summary
- Manufacturer
- Alpha
- Fault code
- 05
- Fault type
- Central heating, Temperature sensor
- Severity
- Not specified
- Reset
- Not specified
- Applicable models
- Evoke 28, Evoke 33
Quick answer
CH flow sensor fault.
What does this fault code mean?
CH flow sensor fault.
Common causes
- Incorrect flow sensor resistance value.
- Flow-sensor wiring or sensor fault.
Symptoms
This information was not provided in the verified manufacturer source.
What can the homeowner safely check?
This information was not provided in the verified manufacturer source.
Boiler reset information
Reset information was not provided in the verified manufacturer source. Do not repeatedly reset an unresolved fault.
When should I call an engineer?
Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.
Engineer diagnosis
- Assess CH flow sensor resistance and wiring.
Applicable boiler models
Related fault codes
- 01 — Evoke 28 and 33
Ignition failure; flame not detected during the ignition sequence.
Read fault code - 02 — Evoke 28 and 33
Overheat boiler lockout.
Read fault code - 03 — Evoke 28 and 33
High flue temperature.
Read fault code - 04 — Evoke 28 and 33
Gas-valve electrical connection fault.
Read fault code - 06 — Evoke 28 and 33
DHW sensor fault.
Read fault code - 08 — Evoke 28 and 33
Maximum number of resets reached (five).
Read fault code - 10 — Evoke 28 and 33
Primary system pressure low.
Read fault code - 16 — Evoke 28 and 33
Fan fault.
Read fault code
Manufacturer documentation
Alpha Evoke installation and servicing instructions05 | CH flow sensor fault | Incorrect flow sensor resistance value | Flow sensor wire connections or sensor faulty
Last verified
2026-09-12
Frequently asked questions
What does Alpha 05 mean?
CH flow sensor fault.