70/90 Medium

Grant 70/90 Fault Code

Also written as 7090 — same fault.

The Grant 70/90 fault code means: your boiler is displaying its power output identification code rather than an error, which usually means the system's electronic brain is failing to read the boiler's settings correctly.. It appears on 1 Grant model in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Model and Heat Output (kW/Btu/h) - 20.7 (70 600) / 22.7 (77 500) / 25.6 (87 350)
Typical repair cost £120-250 (including labour)

Engineer required

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

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 70/90: 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.

Grant models that show the 70/90 fault code

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

Source

Grant 70/90 fault code information on this page is sourced and cross-checked against the official Grant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026