Noritz tankless water heater code Er35
Exhaust thermistor open or short. Code Er35 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 Er35 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| NRCP | Exhaust thermistor open or short | Call a pro | $150–$500 |
| NRCP Eco TOUGH | Exhaust thermistor open or short | Call a pro | $150–$500 |
Each row opens the full page for that generation. We hold manuals for NRCP and NRCP Eco TOUGH, and each one gets its own reading of code Er35 — what Noritz documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 2 series in four columns, which is enough to route you and not enough to explain anything. This is the Noritz wording behind each row, one entry per manual, so you can see where the 2 readings of code Er35 agree and where they part company.
NRCP — Exhaust thermistor open or short
The exhaust sensor is open circuit or short circuit. Noritz gives it the same remedies as the water-side thermistors, but its position makes it a different proposition: it sits in the flue, and it is the input behind Er94, the exhaust overheating code.
NRCP Eco TOUGH — Exhaust thermistor open or short
The exhaust sensor is open or short circuit. Same remedies as the other three sensors, same auto reset — but a different proposition, because this one sits in the flue and is the input behind Er94.
Does it matter which Noritz you have?
NRCP and NRCP Eco TOUGH all route code Er35 the same way: a professional, at $150–$500. That makes it one of the Noritz numbers you can act on before working out which unit you own.
What to check first, whatever your series
These checks are on the manufacturer's list for every Noritz series that reports code Er35, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- Call a licensed professional. The sensor is in the exhaust stream and the work around it is combustion work.
That is 1 of the 1 checks documented for code Er35. The rest differ by generation, so if none of those explains it, go to your own series above.
Which Noritz do you have?
On the 2 series that report code Er35, the model number on the rating label starts NRCP — match yours against the 4 listed below. You can also 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 Er35
Code Er35 on these 2 Noritz series points at 1 part and 2 symptoms, each named by the manufacturer's own procedure for this code.