Boiler displays E1 338, often intermittent, affecting temperature readings.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Faulty return NTC sensor, Loose or corroded sensor connector, Damaged harness between sensor and PCB, PCB sensor circuit fault

Safety first: Isolate electrical power before removing any covers.

Reset and observe: Reset the boiler and see if heating or hot water runs normally. If the error reappears, a sensor or wiring issue is likely.
Check for leaks: Look for any signs of water around the return pipework and sensor area that could affect the sensor or wiring.
Engineer tasks: A qualified engineer should measure the NTC resistance at different temperatures, check plug connections on the PCB, and replace the return sensor or PCB if readings are out of specification.

Hard 4/5

Return Temperature Sensor (NTC)

Check Price on Amazon

We may earn a commission from links on this page.