How Can I Tell If The Heater Is Working?

If your washing machine isn't heating up the water, it should do one of two things

Stick indefinately on the wash section of the program and have to be moved on manually

Abort the program with an error code or flashing lights

If your washing machine is very old it should do the former, but most washing machines made in the last 10 - 15 years should do the latter. If the washing machine completes the wash cycle on its own but you suspect it isn't heating the water because either you can't feel the glass getting hot or because of poor wash results then the chances are the washing machine is heating the water though some washing machines appear to have anomalies whereby a fault stopping the heater from working does not trigger an error code as it should. For trouble shooting guide see this article - Washing machine isn't heating up the water

Troubleshooting a washing machine not heating involves checking to see if there is a broken wire or connection in the harness or on the actual heater itself and testing the heater's continuity with a continuity test meter (multi meter) Heaters are usually about 40 Ohms.

( Related: Washing machine stops with an error code | Washing machine stops with lights flashing