You're on site. The boiler is showing a fault code you haven't seen before. You could spend time searching through a manual you might not have, or you could type the code into GasVault and get a detailed diagnosis in under ten seconds.
GasVault's AI fault diagnosis tool is built specifically for Gas Safe engineers. It understands boiler fault codes in technical terms, skips the obvious steps, and gives you the specific components to check and the expected readings to find.
How It Works
Open the Fault Lookup tool from the GasVault dashboard. Enter the fault code and the boiler brand. The AI returns:
- Cause — the most likely reason for the fault code
- Diagnostic steps — specific components to check, with expected voltage or resistance readings where relevant
- Likely parts — what you're most likely replacing
- Brand-specific notes — known quirks or common failure patterns for that manufacturer
Here's an example of what a diagnosis looks like for a common Vaillant fault:
Check:
1. Check system pressure gauge — should read 1.0–1.5 bar cold. If below 0.5 bar, low pressure confirmed.
2. Inspect all visible pipework and radiator valves for signs of a leak.
3. Check the filling loop — ensure it's not left open (common cause of slow pressure loss).
4. If pressure drops repeatedly after topping up, suspect a failed pressure relief valve or a leak in the system. PRV discharge pipe — check if damp or dripping at the termination point.
Parts: Pressure relief valve (if weeping), auto air vent if air ingress suspected.
Note: On ecoTEC Plus, persistent F.22 after top-up often indicates a failing expansion vessel — check pre-charge pressure (should be 0.75 bar cold, system drained).
That's engineer-to-engineer communication — no disclaimers, no obvious steps, just the specific information you need to diagnose the fault efficiently.
Follow-Up Questions
The AI maintains context across the conversation. If the initial diagnosis doesn't resolve it, you can ask follow-up questions:
- "Pressure is fine but the fault persists — what else?"
- "Where is the PRV on this model?"
- "What resistance should I read across the flow sensor?"
Each follow-up gets a contextual answer based on the original fault code and brand. You're not starting the conversation again from scratch.
Boiler Brands Supported
For the most common brands — Vaillant and Worcester Bosch — GasVault also has a local verified fault code database that the AI uses as its primary source, so the most common faults return pre-verified step-by-step guides rather than AI-generated responses.
Boiler Age Lookup
GasVault can also estimate a boiler's manufacture date from its serial number. Enter the serial and brand, and the AI decodes it — useful when advising a customer on whether repair or replacement makes more economic sense, or when verifying the boiler history before a service.
Service Mode Guides
The Boiler Hub in GasVault also stores service mode entry sequences for popular models. Need to enter service mode on a Worcester Greenstar to check flow temperature or run a pump test? It's in the app. No more hunting through a PDF manual on your phone.
Why This Matters
A quicker diagnosis means less time on site per job. If you're running 4-5 repair callouts a day, shaving 10-15 minutes off each diagnosis adds up to over an hour saved daily. That's an extra callout per day, or finishing on time instead of running late.
It also means fewer second visits. Getting the right diagnosis first time means you order the right parts first time — which directly affects your profit margin on repair jobs.
Try the fault diagnosis tool on your next job
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