Baxi Suprima 70 Fault codes & diagnostics

3 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Regular Natural Gas 20.5 kW 1999-2010 Discontinued
GC Number 41-607-79

Replaced by: Potterton Promax HE

Download the Baxi Suprima 70 manualThe official installation and service manual (PDF). PDF

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Just want the most common Baxi Suprima 70 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 3 documented codes

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Lockout

Your boiler has safely shut itself down because it failed to ignite properly.

High DIY-safe £100-£250

What to check first

  1. Check that your gas supply is working by testing another gas appliance like a hob.
  2. Locate the reset button on your Baxi Suprima, press it firmly, and hold it for about 5 seconds.
  3. Wait to see if the boiler fires up normally; do not repeat this more than twice if it fails again.

Parts commonly replaced

  • PCB
  • Ignition lead
  • Gas valve
Full explanation for Lockout