What does the Ideal H9/L9 fault code mean?

Your boiler has detected that it is running much hotter than it should be and has shut itself down to prevent any internal damage.

How much does it cost to fix Ideal error code H9/L9?

Typical repair cost for the Ideal H9/L9 fault is £150-350 including labour.

HEAT EXCHANGER OVERHEAT (With V9 Primary Control PCB, will display 3 horizontal lines upon reset and not refire until temperature drops below 50oC)

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

Each noise points to a different fault.

Almost always a stuck diverter valve on combis.

Sludge build-up — needs flushing, not bleeding.