The Noritz PCB is the unit's central computer. Reads sensors, drives gas valve, runs ignition, manages modulation, logs faults. When it fails, behavior becomes erratic and codes don't map cleanly.
Symptoms suggesting PCB failure
- Multiple unrelated error codes in rapid succession
- Display garbled or blank with power confirmed
- Random restarts mid-operation
- Buttons not responding
- Modulation not happening (burner stuck at one fire level despite setpoint changes)
Diagnose by elimination
PCB failure is the diagnosis of last resort. Work through the relevant code's diagnostic sequence first. PCBs are robust and rarely fail before year 8-10.
Replacement
Dealer-only. PCBs come pre-flashed with model-specific firmware.
Cost
- OEM PCB: $400-800 model-dependent
- Labor: $250-500
- Total: $650-1,300
NCC cascade controller (separate part)
The cascade controller is a separate Noritz-proprietary device that orchestrates multi-unit cascade installs. Failure of the cascade controller doesn't affect individual unit operation — units default to standalone mode. Cascade controller replacement: $1,500-3,000, dealer-only.
Warranty
5-year parts warranty includes PCB. Outside warranty, PCB cost approaches 30-40% of new unit price.
Bottom line
10+ year-old unit with PCB failure → replacement makes more sense than repair. Inside warranty → replace PCB. For cascade installs, the controller and individual unit PCBs are separately repairable.