Rheem tankless water heater displays E20 and will not operate.

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

Damaged remote controller cable, incorrect wiring polarity, faulty remote controller, faulty main control board communication circuit.

Safety first: Turn OFF power before working on low-voltage wiring.

Check cable routing: Inspect the cable between the heater and remote controller for cuts, staples through the wire, or tight bends.
Verify connections: Ensure the remote cable is connected to the correct terminals on both the heater and the remote. Observe polarity if specified.
Test without remote: Disconnect the remote controller and try operating the unit using the onboard controls (if available). If the unit works, the remote or cable is faulty.
Replace components as needed: Replace the remote controller cable first, then the remote itself if E20 persists. If still present, the main control board may need replacement.

Medium 3/5

Remote Controller Cable

Check Price on Amazon

We may earn a commission from links on this page.