Potterton E128 Fault Code (Assure Combi & System)

Safety disclaimer

Fault code summary

Manufacturer

Potterton

Fault code

E128

Fault type

Flame failure, Safety lockout

Severity

lockout

Reset

Not specified

Applicable models

Potterton Assure Combi, Potterton Assure System

Quick answer

Safety error for frequent loss of flame.

What does this fault code mean?

Safety error for frequent loss of flame.

Common causes

• Frequent loss of flame.

Symptoms

• The boiler displays E128 and may lock out.

What can the homeowner safely check?

• Note the code and contact a qualified engineer if it repeats.

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

• Investigate flame sensing, ignition, gas supply and combustion by qualified personnel.

Applicable boiler models

• Potterton Assure Combi
• Potterton Assure System

Related fault codes

• E09 — Assure Combi & System

  Gas valve connection fault.

  Read fault code
• E10 — Assure Combi & System

  External probe fault.

  Read fault code
• E109 — Assure Combi & System

  Precirculation alarm.

  Read fault code
• E110 — Assure Combi & System

  The boiler maximum temperature was exceeded, or the safety thermostat sensor tripped.

  Read fault code
• E118 — Assure Combi & System

  Water pressure is low, below 0.5 bar.

  Read fault code
• E12 — Assure Combi & System

  Differential water-flow switch fault; the switch is still open.

  Read fault code
• E125 — Assure Combi & System

  Water circulation fault.

  Read fault code
• E129 — Assure Combi & System

  Safety error for frequent loss of flame with maximum correction during ignition calibration.

  Read fault code

Manufacturer documentation

Potterton Assure Combi & System — E128: Safety error for frequent loss of flame.

Last verified

2026-09-12

Frequently asked questions