High
Dry fire sensor on Potterton Envoy Plus

Your boiler has lost the ability to detect if there is enough water inside, so it has safely shut down to prevent damage.

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

Sensor failed open or closed circuit

From this model's manual
Verified against the Potterton/Potterton Envoy installation & service manual, page 25.
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.

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 Dry fire sensor: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

All 24 fault codes on the Envoy Plus

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

Case sensorCase temperatureControl failedDisplay not illuminatedDry fireFan speedFlame lossFlashingFlow sensorHot Surface IgniterLockoutPulse Red (1 flash)Pulse Red (2 flashes)Pulse Red (3 flashes)Pulse Red (4 flashes)Pulse Red (5 flashes)Pulse Red (6 flashes)Return sensorSensorShorted signalShut downStand-byWiring fault

Related guides you might find useful

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

New boiler cost 2026

Realistic UK prices for a swap.

Read →