High
CH PUMP indicator Slow flash on Grant Vortex 20-26

Your boiler's internal control brain is experiencing an electronics failure and can no longer reliably signal the system to move hot water around your home.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Slow flash (once every 2 seconds): Indicates a possible fault with the PCB (relay). Replace PCB.

From this model's manual
Verified against the Grant Vortex Pro Internal Combi Installation Servicing Instructions DOC88 Rev00 May 2012 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

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

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All 23 fault codes on the Vortex 20-26

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

BURNER (FLASHING)BURNER indicator flashingBURNER indicator Slow flashCH PUMP Fast flashCH PUMP indicator Fast flashCH PUMP Slow flashDHW PUMP (FLASHING)DHW PUMP Fast flashDHW PUMP indicator Fast flashDHW PUMP indicator Slow flashGREEN blinking (0.5s)GREEN ORANGE blinking (0.5s)GREEN, RED blinkingGreen/Red flashingLock-out (light on)Lockout button litLOW PRESSURE indicator litRED blinking (0.5s)RED fast blinking (0.2s)RED flashing (Reset button)RED, GREEN blinking invertedRED, ORANGE blinking inverted

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