BoilerFaultCodesGrant Vortex Blue Fault codes & diagnostics
0 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
System Oil 15-36 kW 2016-present
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The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Status & diagnostic codes 8 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
8 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
0 4 Diagnostic Your boiler is warning you that the water in your area is extremely hard, which causes significant scale build-up inside the internal components and will eventually prevent the unit from heating water efficiently. 1 3 Diagnostic Your boiler is detecting high levels of limescale build-up in your water system, which can reduce efficiency and lead to blockages over time. 2 2 Diagnostic Your boiler has detected that your home's water is moderately hard, which may lead to limescale buildup over time if not managed. 3 1 Diagnostic Your boiler has detected that the water inside the system is soft, meaning it contains very low levels of limescale. 4 0 Diagnostic Your boiler is alerting you that the water in your heating system is exceptionally soft, which may cause corrosion over time. 21.0 Diagnostic This is not actually a fault code, but rather a display indicating the power output setting of your boiler. 26.0 Diagnostic Your boiler is displaying its maximum heating output setting rather than a fault, meaning the system is currently operating normally. 36.0 Diagnostic This code indicates your boiler model is configured for a 36kW output and is functioning normally, rather than signaling a fault.
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