43
Noritz Internal Circulation Pump / Flow Control Fault (models equipped with pump)

Error code 43 displayed; unit may not operate.

Advertisements

Safety Warning

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.

Advertisements

Possible Causes

Failed internal circulation pump, Airlock in pump or piping, Blocked check valve, Pump wiring or control fault

How to Fix / Troubleshooting

Safety first: Turn OFF power and gas. Close water isolation valves before opening any plumbing connections.

Steps to check and correct:

  • Bleed air from system: If your Noritz model has an internal pump for recirculation, open a nearby hot water fixture and allow water to run to purge air. Some systems have manual bleed valves; follow the installation manual.
  • Check pump operation: With the front cover removed and power restored briefly, listen for the pump running when a recirculation call is active. Turn power back off before touching anything.
  • Inspect pump wiring: Ensure the pump connector is secure and wires are intact.
  • Check for blocked valves: Verify that any recirculation isolation valves and check valves are open and not stuck.
  • Professional service: If error 43 continues, the internal pump or PCB pump driver may be defective and should be replaced by a qualified technician.
Advertisements

Repair Difficulty

Hard 4/5

Required Part

Internal Circulation Pump
Check Price on Amazon

We may earn a commission from links on this page.

Advertisements