Noritz error code Er31
Cold water thermistor open or short. Code Er31 means the same thing on all 2 Noritz series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code Er31 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| NRCP | Cold water thermistor open or short | Part replacement | $120–$400 |
| NRCP Eco TOUGH | Cold water thermistor open or short | Part replacement | $120–$400 |
Each series links to the full page: what the manufacturer's manual says for that generation, what you can safely check yourself, and what the repair should cost.
How much the answer changes between series
Every Noritz series that documents code Er31 routes it the same way: a replacement part. That is unusual enough to be worth saying, because on this brand the same number often means different work on different generations. Here it does not — so you can act on this page without first establishing which unit you own.
The cost is documented the same way across all 2 series: $120–$400, depending on which of the manufacturer's causes turns out to be yours.
Which Noritz do you have?
The model number is on the rating label on the unit itself. Match it against the list below — or use the full model-number decoder.
Where this comes from
Source: Noritz Service Manual — NRCP111-DV / NRCP98-DV (Rev. 09/19) (p. 62), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Source: Noritz Service Manual — NRCP1112-DV / NRCP982-DV Eco TOUGH (Rev. 05/19) (p. 58), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Parts, guides and symptoms behind code Er31
Everything the 2 Noritz series point at for this code, in one list. A part named here is one the manufacturer's own procedure reaches for.