Rinnai tankless water heater code 19
Electrical grounding fault. Code 19 means the same thing on all 3 Rinnai series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code 19 means on each Rinnai series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| Non-SENSEI | Electrical grounding fault | Call a pro | $150–$800 |
| SENSEI | Electrical grounding fault | Call a pro | $150–$800 |
| SENSEI RX | Electrical grounding fault | Call a pro | $150–$800 |
Each row opens the full page for that generation. We hold manuals for Non-SENSEI, SENSEI and SENSEI RX, and each one gets its own reading of code 19 — what Rinnai documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 3 series in four columns, which is enough to route you and not enough to explain anything. This is the Rinnai wording behind each row, one entry per manual, so you can see where the 3 readings of code 19 agree and where they part company.
Non-SENSEI — Electrical grounding fault
An electrical fault in the heater's DC circuit. Rinnai's note is specific and useful: a code 19 that appears the moment water starts flowing, with no flame visible in the burner box, means a short in one of the unit's components — a wiring harness, the water flow control or bypass valve, or anything else on that circuit. The technician's method is to unplug one component at a time until the unit will cycle.
SENSEI — Electrical grounding fault
The heater has detected a grounding problem in its own circuit. Rinnai groups code 19 with an immediate code 12: if it appears as soon as water starts flowing and no flame is visible in the burner box, the fault is an electrical short in one of the unit's components — a wiring harness, the water flow control, the bypass valve, or anything else on the DC circuit.
SENSEI RX — Electrical grounding fault
The heater has detected a grounding problem in its own electrical circuit. Rinnai groups code 19 with an immediate code 12: if it appears as soon as water starts flowing and no flame is visible in the burner box, the fault is an electrical short in one of the unit's components — a wiring harness, the water flow control, the bypass valve, or anything else on the DC circuit.
Does it matter which Rinnai you have?
Non-SENSEI, SENSEI and SENSEI RX all route code 19 the same way: a professional, at $150–$800. That makes it one of the Rinnai numbers you can act on before working out which unit you own.
Which Rinnai do you have?
On the 3 series that report code 19, the model number on the rating label starts C, RC, RU, RUC and RUR — match yours against the 76 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 31), read Aug 2026 — the manufacturer's own documentation for this Rinnai range.
Parts, guides and symptoms behind code 19
Code 19 on these 3 Rinnai series points at 1 part and 2 symptoms, each named by the manufacturer's own procedure for this code.