How to Fix ATAG 051 Fault Code (No Flame At Ignition) UK
ATAG 051 means no flame at ignition. UK diagnosis, parts to order, reset sequence.
What 051 means
ATAG 051 indicates no flame at ignition. The boiler will lock out and refuse to fire until the fault is cleared.
Do not simply reset — 051 is stored in the ATAG error log and will re-trigger within minutes if the underlying part has failed.
Diagnostic sequence
Enter service mode on the ATAG boiler and read the flow/return/DHW temperatures, fan PWM, ionisation current and pump speed.
Cross-reference against the ATAG technical manual — 051 typically points to two or three candidate parts.
- Check wiring harness continuity to the suspect sensor before condemning it.
- Isolate at the fused spur, discharge and re-inspect connectors.
- Measure resistance / voltage at the PCB plug per ATAG test procedure.
Parts to have on the van
Carry a set of NTC sensors, an ignition electrode kit and a fan for ATAG — these three parts clear >70% of 051 call-outs.
Recommission
After the fix, run the ATAG boiler through a full flow test, gas rate, and combustion analysis. Log to the Benchmark book to preserve manufacturer warranty.
Frequently asked questions
- Can I reset 051 without changing parts?
- Only if the fault has cleared (e.g. low pressure repressurised). Persistent 051 means a hardware failure.
- Which is the most common cause of ATAG 051?
- On ATAG boilers, 051 most often points to the sensor or actuator matching its meaning (no flame at ignition); check wiring and connector integrity first.
- Is a Gas Safe engineer required?
- Yes — any works past the boiler case seal require a Gas Safe registered engineer under UK law.
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