Noritz NRCP Code Er43
Burner high limit switch fault. The high limit switch at the burner has tripped. Noritz's remedies are to check the flame condition through the burner window, check the air intake filter, and check for gasket damage around the burner. The last one matters: a failed gasket on a sealed combustion chamber lets combustion products where they should not be.
Also displayed as: 43, E43
Call a proThe verdict
Call a licensed plumber
Cleaning the air intake filter is yours and free. The rest is inside a sealed burner chamber, and one of Noritz's three named causes is a damaged gasket around it — which is a reason to leave the unit off rather than keep trying.
Typical cost: $0–$1,200
US estimate for parts and labor. Prices vary by region and by who does the work — see how we estimate costs.
What the manual says
The meaning above is transcribed from the manufacturer's diagnostic documentation for the NRCP — not averaged across the brand.
Source: Noritz Service Manual — NRCP111-DV / NRCP98-DV (Rev. 09/19) (p. 62), read Sep 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- Clean the air intake filter — Noritz's one homeowner remedy for this code.
- Do not open the burner chamber or inspect the gasket yourself.
- Call a licensed professional, and mention that Noritz lists burner gasket damage as a cause so they bring the part.
Code Er43 on other Noritz series
The same code number can mean something different on another series — make sure you're reading the page for your exact unit:
Don't confuse this with
3 other Noritz NRCP codes point at a switch too. They are different components in different places, and ordering a part against the wrong one is the most common way this fault gets expensive: