HeatingCodes

Bradford White D-series (24 V Honeywell / ICON HD) error codes

By Jason Dearmin · Last reviewed November 14, 2026

This table comes from Bradford White's quick service guide for its commercial D-series heaters. The guide pairs each error code with a service action and the parts most often involved, and it opens with a reminder to verify gas pressure, wiring, vent restrictions and leaks before troubleshooting.

What this table coversBradford White Quick Service Guide 238-55600-00 for commercial induced-draft damper electronic-ignition D-series water heaters with the 24 V Honeywell integrated control / ICON HD. It is not a table for every Bradford White water heater.

How to read the display

If your heater has no display, the guide says to check the primary and secondary voltage first.

Before troubleshooting any code, Bradford White says to verify: gas inlet pressure; static-to-dynamic gas pressure drop; no vent restrictions; all wire connections tight; no grounded wires or missing grounds; and no water leaks.

Bradford White code table

CodeMeaningWhat the document says
2 Pressure switch failed to open Verify the pressure switch is closed (as written in the guide) and check for vent restriction. Part involved: pressure switch.
4 Low flame sense signal Check micro-amps; inspect the pilot assembly and wires. Parts involved: pilot assembly, control board.
6 Flame sensed out of normal sequence Verify the pilot is present, check whether the gas valve is powered by 24 V, inspect the pilot for grounding. Parts involved: gas valve, control board, pilot assembly.
18 Gas valve fault Change the gas valve.
23 Flame detected before ignition Verify whether the pilot is present, check whether the gas valve is powered by 24 V, inspect the pilot for grounding.
24 Flame detected after heating cycle completes Verify whether the pilot is present, check whether the gas valve is powered by 24 V, inspect the pilot for grounding.
29 Pressure switch failed to close Verify the pressure switch is open (as written in the guide) and check for vent restriction. Part involved: pressure switch.
31 Upper temperature sensor: incorrect reading Measure resistance of the upper sensor. Parts involved: upper temperature sensor, control board.
32 Lower temperature sensor: incorrect reading Measure resistance of the lower sensor.
55 Damper safety switch not proved: damper stuck closed Verify operation; the damper should open and close under its own power.
56 Damper stuck open Verify operation; the damper should open and close under its own power.
57 Flame sensor shorted to ground Inspect the flame sensor wire, the pilot assembly and the pilot shield. Parts involved: pilot assembly, pilot shield, control board. Full explanation
58 Power supply problem (line voltage) Verify proper supply voltage, grounding and polarity.
59 Line voltage too low or high Verify that a dedicated circuit is being used.
61 DC voltage unstable Verify transformer output is 22 to 27 Vac. Parts involved: control board, transformer.
62 Ignition failure Verify gas pressure; inspect the pilot assembly; test for 24 V from the control to the pilot valve. Parts involved: pilot assembly, control board, gas valve.
63 Ignition failure Verify gas pressure; inspect the pilot assembly; test for 24 V from the control to the pilot valve. Parts involved: pilot assembly, control board, gas valve.
64 Electronics failure Check all electrical connections, verify supply voltage, grounding and polarity, and eliminate or replace any components that are wet or damaged.
65 High water temperature (over 200°F) Measure resistance of the upper sensor. Parts involved: upper and lower temperature sensors, control board.

Source: Bradford White 238-55600-00A. Codes outside this list are not covered by this guide.

Detailed explanations

SafetyThese tables describe what the manufacturer documents say. Gas, combustion, refrigerant and line-voltage repairs are for licensed professionals. If you smell gas, leave the building and call your gas utility or 911. Safety disclaimer.

Sources