Potterton E133 Fault Code (Assure Combi & System)

Safety disclaimer

Fault code summary

Manufacturer

Potterton

Fault code

E133

Fault type

Gas supply, Ignition, Flame failure

Severity

lockout

Reset

Not specified

Applicable models

Potterton Assure Combi, Potterton Assure System

Quick answer

Gas supply fault.

What does this fault code mean?

Gas supply fault.

Common causes

• Gas supply fault.
• The source table also directs checks of the power supply, sensing electrode, spark electrode and cable.

Symptoms

• The boiler displays E133 and may fail to ignite.

What can the homeowner safely check?

• Check only that the appliance has power and that other gas appliances have not also lost supply; do not work on gas components.

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 gas supply, ignition electrodes, flame sensing and associated cabling.

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
• E128 — Assure Combi & System

  Safety error for frequent loss of flame.

  Read fault code

Manufacturer documentation

Potterton Assure Combi & System — E133: Gas supply fault. Check the power supply, sensing electrode, spark electrode and cable.

Last verified

2026-09-12

Frequently asked questions