Verified boiler fault code
Ariston 501 Fault Code (Cares ONE NG)
No flame detection.
Safety disclaimer
Fault code summary
- Manufacturer
- Ariston
- Fault code
- 501
- Fault type
- Ignition, Flame failure
- Severity
- lockout
- Reset
- The manual says an operation shutdown may be reset with the reset button, but limits resets to five in 15 minutes and requires a technician if the fault returns.
- Applicable models
- Ariston Cares ONE NG
Quick answer
No flame detection.
What does this fault code mean?
No flame detection.
Common causes
- No flame detected.
Symptoms
- The display shows Err/501 and operation shuts down.
What can the homeowner safely check?
- Check only that the boiler has power and whether other household gas appliances are affected.
Boiler reset information
The manual says an operation shutdown may be reset with the reset button, but limits resets to five in 15 minutes and requires a technician if the fault returns.
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
- Investigate gas supply, ignition, flame detection and combustion by a qualified engineer.
Applicable boiler models
Related fault codes
- 101 — Cares ONE NG
Overheating.
Read fault code - 103 — Cares ONE NG
Insufficient circulation.
Read fault code - 104 — Cares ONE NG
Insufficient circulation.
Read fault code - 105 — Cares ONE NG
Insufficient circulation.
Read fault code - 106 — Cares ONE NG
Insufficient circulation.
Read fault code - 107 — Cares ONE NG
Insufficient circulation.
Read fault code - 108 — Cares ONE NG
Insufficient water; filling is requested.
Read fault code - 305 — Cares ONE NG
PCB error.
Read fault code
Manufacturer documentation
Cares ONE NG - User ManualOperation shutdown error table: No flame detection — 5 01; the example display shows Fault 501 and Press RESET.
Last verified
2026-09-12
Frequently asked questions
What does Ariston 501 mean?
No flame detection.
Can I reset a Ariston 501 fault?
The manual says an operation shutdown may be reset with the reset button, but limits resets to five in 15 minutes and requires a technician if the fault returns.