Takagi water heater shows error 721; unit does not respond to remote.

Safety first: Turn OFF power before disconnecting the remote.

Steps:

• 1. Power cycle: Turn OFF power to the heater for 1 minute, then ON. See if the error clears.
• 2. Inspect remote: Check for water damage, cracked housing, or signs of impact.
• 3. Disconnect remote: Disconnect the remote cable at the heater. If the heater operates in default mode without the remote, the remote is likely faulty.
• 4. Replace remote: Install a compatible Takagi remote controller and test.