Microwave displays E4 and will not heat

Safety: Unplug the microwave before cleaning or removing any covers.

• Clean the interior: Steam and food residue can coat the humidity sensor. Thoroughly clean the cavity walls and ceiling with a mild detergent solution. Wipe dry.
• Locate and clean sensor: The humidity sensor is often a small grille or opening on the top or side of the cavity. Gently clean around this area with a soft cloth; do not spray cleaner directly into the sensor opening.
• Power reset: After cleaning, leave the door open to dry for 30 minutes, then plug the unit back in and test.
• Internal check (advanced): If E4 remains, the sensor module behind the cavity wall may be faulty. With the outer cover removed (unplugged), locate the humidity sensor assembly and check its connector for corrosion or loose fit.
• Replace sensor if needed: If the sensor is physically damaged or tests out of specification, replace it with a Haier-compatible humidity sensor module.
• Control board fault: If a new sensor does not clear E4, the main PCB may be defective and should be replaced by a technician.