LED 1 Fast Flashing (8Hz) High

Glow-worm LED 1 Fast Flashing (8Hz) Fault Code

Also written as LED1FASTFLASHING8HZ — same fault.

The Glow-worm LED 1 Fast Flashing (8Hz) fault code means: your boiler’s internal control board has developed a critical electronic fault and can no longer manage the heating process safely.. It appears on 4 Glow-worm models in our database.

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.

Technical description: PCB Failure

What causes the Glow-worm LED 1 Fast Flashing (8Hz) fault?

This fault occurs when the boiler's internal electronic brain suffers a hardware failure, preventing it from processing information from the sensors. The most common reason is the natural degradation of electrical components on the circuit board over time, or a sudden voltage spike that has damaged the delicate circuitry. Because the board can no longer guarantee the boiler is operating safely, it shuts the system down entirely.

Typical repair cost £220-£380 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Glow-worm models that show the LED 1 Fast Flashing (8Hz) fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Glow-worm LED 1 Fast Flashing (8Hz) fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026