Baxi E1 Fault

Baxi E1 Fault

The Baxi E1 error code is often followed by another number (such as E1 19, E1 31, etc.), which indicates that the boiler’s temperature sensors (known as NTC thermistors) are a problem. These monitor the water temperature in the boiler and heating system, but ‘faults’ in their readings can lead to various operational issues. The numbers following the E1 code can sometimes reveal what is specifically wrong.
Causes of E1 Error Codes

Bad Thermistor: Ageing or some damage may cause a thermistor to fail thus giving wrong temperature readings.

Problems with Wiring: This could be due to loose or damaged wiring connections between thermistors and control boards that send erroneous signals.

Accumulation of Sludge/Scale: This happens when there is sludge or scale build up within the system it affects negatively water temperatures around NTC, thus presenting false readings.

Poor Circulation: The vacuum inside tube will reduce head space such that less liquid will fill into space therefore this may affect its detection by NTC while also airlock; pump defects may be responsible for this condition and related cases of poor circulation.

Different E1 Error Code Variations And Their Rectification

E1 19 (Flow NTC Fault) means there is something wrong with a sensor that measures how hot water coming from a boiler has become. Check for any damages on cables and sensors themselves while making sure nothing out of place happens like sludge affecting them.

E1 20 (Return NTC Fault) indicates an issue with the sensor detecting how cold water getting back to a heater has actually become. Such checks would apply just as they did for the flow NTC fault

E1 31 (Supply Voltage Too Low): Though not purely relating to thermistor itself, this signifies that your boiler receives insufficient power supply voltage which could interfere with functions of sensors.

Resolving E1 Error Codes

Cleaning and checking of Thermistors: If possible, look to see if any damage or dirt has occurred on the thermistors themselves. Cleaning it may sometimes help.

Checking Wiring Connections: To this end, make sure that everything is well connected starting with the control board and going down to the thermistors.

Ensure Proper System Bleeding/Circulation: By bleeding radiators and checking out how pump works for any airlocks, one address circulation problems within a system.

Resetting a Boiler: After addressing potential issues, reset the boiler to clear the error code and retest the system.

Professional Support: Because diagnosing and repairing NTC thermistor and electrical component related issues are usually technical, getting an accurate diagnosis plus safe repairs needs an expert registered Gas Safe engineer.

Routine Maintenance: Regular professional maintenance can avoid future E1 error codes. This will ensure that your circuits remain in good working conditions as well as other crucial parts such as Thermostats.


The Baxi E1 error code shows there are temperature sensing problems inside the boiler system. While owners can do some basic checks, resolving these underlying causes often requires professional intervention. Regular servicing can prevent such incidents from happening again hence maintaining efficiency as well as reliability in running boilers.