If you suspect that your washing machine is not heating up the water (either because the appliance doesn't feel warm during the wash cycle or because your clothes are not being cleaned properly), this may be due to a fault with the heating element. 

When there is a fault with the heating element you would normally see an error code on the display. 

Unless you are an expert, this is not a repair we would recommend you try to undertake yourself.  A qualified repair engineer should be able to resolve the issue by installing a replacement heating element.