High
02 on Vokera Synergy E

Your boiler has reached an unsafe temperature because water isn't circulating properly through the system.

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

Flow/return valves closed; Stuck pump. Appears if the boiler has overheated.

From this model's manual
Verified against the Vokera Synergy E installation & service manual, page 53.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when water cannot travel through the boiler’s internal pipework fast enough to carry away the heat, leading to a build-up of extreme temperature. The most common reasons are a pump that has seized up or internal blockages that are preventing the water from flowing freely through the system.

This issue is frequently seen at the start of autumn when heating systems are switched back on after being idle all summer, which can cause the pump to stick.

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 →

Avoid the next call-out bill

A cover plan would handle faults like 02: 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.

Related fault codes

Related guides you might find useful