High
Overheat (Red LED) on Baxi Solo 3 40 PF

Your boiler has detected that it is running too hot and has automatically shut itself 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

The Red LED will illuminate if the overheat thermostat has operated.

From this model's manual
Verified against the Baxi Boiler Solo 3 50 Pf 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.

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 Overheat (Red LED): 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 23 fault codes on the Solo 3 40 PF

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

Boiler On (Orange LED)Boiler On light onBurner LED GreenBurner On light offFan/Flue LED GreenIndicator light inside box litLights: Flash Flash OnLights: Flash Off FlashLights: Flash Off OnLights: On Off FlashLights: On Off OnLights: On On OnLockout light onOverheat indicator lightOverheat Neon IlluminationPeripheral / Pump LED GreenPilot On lightPilot On light onPilot/Ignition LED GreenPower LED GreenPower On (Green LED)Red neon illuminated

Related guides you might find useful

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →