Common problems guide

The most common Ideal RD2 problems

The faults most likely to send a Ideal RD2 into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

This model is discontinued. Parts can be harder to source and expensive. If repair costs are mounting, a new A-rated boiler may be the smarter choice.
8 documented codes
6 most common
0 DIY-safe checks
6 engineer needed

The 6 most common faults

01
Sensor Faults High Engineer

Your boiler has detected an issue with one of its internal heat sensors and has stopped working to ensure safety.

Est. cost
£120-220
Parts
NTC Sensor, Wiring harness
Full guide for Sensor Faults
02
Reverse polarity High Engineer

Your boiler is failing to start because the electrical supply wires have been connected the wrong way around.

Est. cost
£90-150
Parts
External electrical supply wiring, Fused spur
Full guide for Reverse polarity
Parts most often replaced

on the Ideal RD2

NTC SensorWiring harnessExternal electrical supply wiringFused spur

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Ideal shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue
See the full 8-code list for the Ideal RD2

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →