Ariston 306 Fault

Ariston 306 Fault

The Ariston error code 306 shows an external probe fault which is a typical outside temperature sensor or other zone-related heating system temperature checker. It is an important factor that helps the boiler to adjust its performance according to the outside weather thus enhancing efficiency and comfort. If it malfunctions, the boiler will not be able to regulate its output properly.
Causes of Error Code 306

Faulty External Probe: The probe itself may not be working correctly, and this can result in incorrect or no temperature measurements at all.

Wiring Issues: Inappropriate wiring connections between ext probe and the control unit of the boiler can lead to a failure with data transmission on temperatures.

Incorrect Probe Installation: When installed incorrectly or in an unfavorable position, it cannot measure outdoor/zone temp accurately.

Environmental Damage: Extreme weather conditions and physical damage may affect its performance.

Troubleshooting and Resolving Error Code 306

Inspect the External Probe: Examine the external temperature probe for any visible signs of damaged or worn out parts. When damaged, it must be replaced immediately.

Check Wiring and Connections: Ensure that all connections between probe and boiler’s control unit are fastened well. Any spoilt wires should be fixed or replaced entirely.

Verify Probe Installation: Ascertain whether an external probe has been installed according to manufacturer’s directions so as to take accurate measurements of temperature levels around it.

Protect the Probe from Environmental Damage: Shift location of this sensor if need arise or provide extra protection against environmental threats likely to destroy it.

Resetting Boiler – After handling any issue related with this ext-probe, reset your boiler so as error code can be cleared off after which you will check if your system normalizes again

Professional Assistance – If you’re unable to resolve the error or if the probe needs replacement, it’s advisable to seek help from a qualified technician. A Gas Safe registered engineer can diagnose accurately what is happening before performing repairs including necessary adjustments.

Regular Maintenance – Integrate checks for external probe and its wiring into your routine boiler maintenance. It will help you to identify potential problems that could lead to error codes or interfere with boiler performance.


The Ariston error code 306, therefore, is a symbol of an external temperature probe issue which needs thoroughness in order to ensure that the boiler works efficiently and promptly. For some basic tests and adjustments, residents can carry them out, but, most of the time, this calls for professional skills in detecting and dealing with these issues. In order to avoid such kind of mistakes and keep your heating system in good working condition it’s important to conduct regular maintenance as well as respond quickly whenever there are signs of damage or malfunctioning in the probe.