Verified boiler fault code
Sime ALL 56 Fault Code (Brava Slim HE ErP)
Lock for delivery/return temperature difference above the maximum limit.
Safety disclaimer
Fault code summary
- Manufacturer
- Sime
- Fault code
- ALL 56
- Fault type
- Overheating, Temperature sensor, Circulation
- Severity
- high
- Reset
- The manual lists this as a lock and directs the user to technical assistance; do not repeatedly reset it.
- Applicable models
- Brava Slim HE ErP 25, Brava Slim HE ErP 30, Brava Slim HE ErP 35, Brava Slim HE ErP 40
Quick answer
Lock for delivery/return temperature difference above the maximum limit.
What does this fault code mean?
Lock for delivery/return temperature difference above the maximum limit.
Common causes
- Delivery/return temperature difference above the maximum limit
Symptoms
- ALL 56 alarm displayed
- Boiler operation may lock
What can the homeowner safely check?
- Record the alarm and check the external controls are calling for heat; do not remove the casing.
Boiler reset information
The manual lists this as a lock and directs the user to technical assistance; do not repeatedly reset it.
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
- A qualified engineer should investigate flow and return temperatures, circulation and the relevant sensors.
Applicable boiler models
Related fault codes
- ALL 01 — Brava Slim HE ErP
Flue-gas thermostat fault.
Read fault code - ALL 02 — Brava Slim HE ErP
Low water pressure in the appliance.
Read fault code - ALL 03 — Brava Slim HE ErP
High water pressure in the heating circuit.
Read fault code - ALL 44 — Brava Slim HE ErP
No-flame gas-valve opening-time sum anomaly.
Read fault code - ALL 57 — Brava Slim HE ErP
Lock for the flow-temperature check (open-vent model).
Read fault code - ALL 62 — Brava Slim HE ErP
Self-calibration procedure required.
Read fault code - ALL 72 — Brava Slim HE ErP
Incorrect positioning of the delivery sensor.
Read fault code - ALL 74 — Brava Slim HE ErP
Second delivery sensor fault.
Read fault code
Manufacturer documentation
Brava Slim HE ErP installation, use and maintenance manual (official Sime document 6322841C)Official manual fault table: | ALL | 56 | Lock for ΔT delivery/ return over max limit |
Last verified
2026-09-12
Frequently asked questions
What does Sime ALL 56 mean?
Lock for delivery/return temperature difference above the maximum limit.
Can I reset a Sime ALL 56 fault?
The manual lists this as a lock and directs the user to technical assistance; do not repeatedly reset it.