Rinnai code 19: electrical grounding fault

Code 19 is one of Rinnai's electrical codes. The control board has detected a grounding problem somewhere in the unit's low-voltage circuits.

Rinnai makes several generations of tankless heaters (SENSEI, SENSEI RX/CX and older non-SENSEI models). The meaning below comes from Rinnai's own diagnostic code guide; the exact service steps differ slightly between generations.

What Rinnai says about code 19

Rinnai's diagnostic guide explains that a code 19 appearing immediately after water flow begins, with no flame visible in the burner box, means one of the water heater's components has an electrical short. The short could be in a wiring harness, the water flow control, the bypass valve or any other part on the DC circuit.

A technician tracks it down by unplugging one component at a time and trying to fire the unit. When the heater cycles normally with a part unplugged, that part is the one with the short.

What you can check

• Make sure the heater is plugged into a properly grounded outlet and that the outlet is not on a loose extension cord or adapter.
• Note whether the code started after a storm, a power surge or water getting into the unit. Moisture inside the cabinet can cause shorts.
• Look for water dripping onto the unit from pipes or the vent above it.

How to reset it

1. Close all hot water taps.
2. Turn the water heater off at the temperature controller, wait about a minute, then turn it back on.
3. Open a hot tap and watch whether the code returns.

If the same code comes back, the cause is still there. Resetting over and over is not a repair.

When to call a technician

Testing components one by one means working inside the unit with power connected, so it is not a homeowner job. Tell the technician when the code appears, for example only when a hot tap first opens, because that helps narrow down the faulty part.

See the full list on our Rinnai error codes page.