Medium Warning
E50 on Potterton Promax

Your boiler has detected a problem with the sensor that monitors the temperature for your taps, meaning you may have inconsistent or no hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Domestic hot water sensor fault

What causes this fault?

This fault occurs when the internal sensor responsible for measuring hot water temperature sends an incorrect or missing signal to the boiler's control board. The most common reason is that the sensor has physically failed due to age, or the electrical connection between the sensor and the main terminal has become loose or damaged.

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 →

Related fault codes

E20View →

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →