Repair
Combi Boiler Error Code Diagnosis & Repair
A flashing code is your boiler telling you something specific. Here's how to read it, what's safe, and when to call a licensed gas technician.
Modern combi boilers run constant self-diagnostics and display a fault code when something is wrong — low pressure, ignition failure, a blocked flue, a sensor fault, or an overheat condition. The code is genuinely useful: it points to the system the boiler is unhappy with, which speeds up an accurate repair. What the code does not do is make the repair a DIY job, because nearly every fault involves the gas, combustion or pressurized side of the appliance.
We maintain a brand-by-brand error code library so you can look up exactly what your boiler is reporting before you call. Below is how to respond safely, plus links to the codes for your specific brand.
What's safe to do yourself
- Write down the exact code and which brand/model you have
- Check the system pressure gauge — many codes are simply low pressure
- Confirm the gas supply is on and other gas appliances work
- Reset the boiler once, per the manual, if it's safe to do so
- If the code returns, stop and call a licensed technician
When to stop and call immediately
If you smell gas, see signs of combustion (soot, scorching), get repeated lockouts, or the boiler reports an overheat or flue/CO-related fault, do not keep resetting it. Repeated resets on a real fault can be dangerous. Turn the appliance off and call for a licensed repair.
Look up your error code by brand
Find your boiler's brand below for a plain-English explanation of each code, the likely cause, and what the repair involves.
- Navien, Viessmann, Bosch, Rinnai, Noritz and more in our code library
- Each code page explains cause, urgency and repair
- Clear guidance on what's safe versus what needs a technician
This is not a DIY repair
Combi boilers are gas-fired appliances regulated under the BC Safety Standards Act. Opening the unit, touching the gas valve, or working on the flue without a valid BC gas-fitter licence is both unsafe and illegal. Diagnosing the fault is helpful — fixing it should always be left to a certified technician.
Call 778-909-5731Frequently Asked Questions
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