E20 on a Baxi is a central heating NTC sensor fault, either a short circuit or an open circuit.

A component fault rather than a system fault, and generally one of the more straightforward repairs.

What E20 actually means

The NTC sensor tells the boiler the temperature of the central heating water. Short circuit and open circuit are the two ways that reading can become impossible to trust.

Without a usable temperature the boiler cannot control the burner safely, so it stops.

What you can safely check yourself

Nothing useful. The sensor is inside the appliance.

Worth noting whether the fault appears from cold or only once the boiler has been running, which helps whoever attends.

When to stop, and why

What causes it beyond the simple checks

A failed sensor, a corroded or damaged connector, damaged wiring between the sensor and the board, or a board input fault. Because open circuit can simply mean a disconnected plug, the connections get checked before the sensor is replaced.

How Vantage can help

We are Gas Safe registered under 956889 and cover Hertfordshire, Bedfordshire and Cambridgeshire, with an emergency line answered 24 hours a day. Call us on 01462 506374. See also boiler repair and boiler servicing.

Frequently asked questions

Is E20 serious?

Not in the safety sense, but the boiler will not run until it is fixed.

Will it definitely be a new sensor?

No. A disconnected or corroded plug gives an open circuit reading and costs nothing to reconnect.

What is an NTC sensor?

A temperature sensor whose resistance changes with heat. Boilers use several of them.

Related fault codes

Other Baxi codes: E09 · E10 · E28 · E110 · E119 · E125 · E128 · E133 · E160 · all boiler advice. See also boiler repair. The same fault on other makes: Ideal F4 · Worcester Bosch E2.

In Baxi’s own words

Baxi use different code sets across their ranges and generations. The definition above comes from The Baxi error code table. If your boiler is a different model and the code behaves differently, check the manual for your appliance or ring us and we will tell you what it means on your unit.

When to call an engineer

If the checks above have not cleared it, the next steps are engineer work and the boiler should not be reset repeatedly in the meantime. Call Vantage Plumbing and Heating on 01462 506374. We are Gas Safe registered under 956889, the line is answered by a person at any hour of any day, and you get a price before anyone starts.

Need help today?

Call and speak to a person, any hour, any day of the year. Get a fixed price quote or call 01462 506374.