12
Call a Pro
Noritz · Tankless Water Heaters
Flame loss after ignition (weak or unstable flame).
Quick Answer
Error code 12 on your Noritz Tankless Water Heaters means: Flame loss after ignition (weak or unstable flame).. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Confirm proper gas type and pressure.
2
Check airflow and venting path.
3
Inspect flame rod condition and wiring.
4
Restart and monitor stability.
5
Call service if flame loss continues.
Pro Tip
This issue typically requires professional diagnosis. Attempting this fix without proper training could cause further problems.
Related Error Codes