What does the Grant 12 fault code mean?

Your boiler is detecting that exhaust fumes are not properly contained, which means there is a potential risk of dangerous gases escaping into your home environment.

How much does it cost to fix Grant error code 12?

Typical repair cost for the Grant 12 fault is £120-250 including labour.

Grant 12 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Combustion fumes smell. Check boiler cleaning cover and seal are correctly fitted. Check burner is correctly fitted onto flange. Check flue is correctly sealed into flue outlet of boiler. Check the condensate pipe and trap are operating correctly.

From this model's manual

Verified against the Grant/Grant Vortex Eco installation & service manual.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

Search the official register →

Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 12: no call-out fees, no surprise bills.

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All 77 fault codes on the Vortex Eco

Seeing a different code? Every code this model can display, in one place.

10 18 21.0 22 26.0 31 36 36.0 44 54 61 69 92 116 143 198 232 286 348 396 429 594 727 728 729 A1.2 A1.3 A2.2 A3.2 Blinking RED BURNER indicator flashing BURNER indicator Slow flash Burner lock-out BURNER Slow flash CH PUMP Fast flash CH PUMP indicator Fast flash CH PUMP indicator Slow flash CH PUMP Slow flash Constant RED DHW PUMP (FLASHING)DHW PUMP Fast flash DHW PUMP indicator Fast flash DHW PUMP indicator FLASHING DHW PUMP indicator Slow flash DHW PUMP Slow flash Fast flash Flashes red Flashes red/green GREEN GREEN blinking GREEN blinking (0.5s)GREEN ORANGE blinking (0.5s)GREEN, RED blinking Green/Red flashing LED off Lock-out Lock-out (light on)Lockout Lockout button lit LOW PRESSURE LOW PRESSURE indicator lit OFF ORANGE ORANGE blinking Overheat Overheat thermostat RED RED blinking RED blinking (0.5s)RED fast blinking RED fast blinking (0.2s)RED flashing (Reset button)RED steady ON RED, GREEN blinking inverted RED, ORANGE blinking inverted Slow flash

Your boiler is detecting that exhaust fumes are not properly contained, which means there is a potential risk of dangerous gases escaping into your home environment.

What the manual says

Engineer required

Avoid the next call-out bill

All 77 fault codes on the Vortex Eco

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