E06 on display, unit will not fire; temperature readings may be erratic or show unrealistic values.

Safety: Turn off power to the water heater before accessing the control compartment.

• 1. Locate the supply sensor: On Triangle Tube water heaters, the supply NTC sensor is typically mounted on the outlet pipe or directly on the heat exchanger. Refer to the unit's schematic label.
• 2. Inspect wiring and connector: Check the sensor harness for cuts, abrasions, or melted insulation. Ensure the plug at the sensor and at the main control board is fully seated and corrosion-free.
• 3. Check for water damage: Look for signs of leaks dripping onto the sensor or wiring. Repair any leaks before replacing components.
• 4. Basic resistance check (if you have a meter): With power off and sensor disconnected, measure resistance across the sensor. Compare to the Triangle Tube temperature/resistance chart. A reading of near 0 Ω (short) or infinite (open) indicates a bad sensor.
• 5. Replace sensor if faulty: If wiring is intact and readings are out of range, replace the supply NTC sensor with an OEM Triangle Tube part. Ensure good thermal contact and reinstall any insulation.
• 6. Reset and test: Restore power, clear the error, and verify that the displayed supply temperature is reasonable and stable.