Unit displays E006 and will not operate; may occur immediately at startup.

Safety: Turn off power before accessing the control compartment.

Steps:

• 1. Locate inlet sensor: Find the cold water inlet temperature sensor on the Lochinvar heater (usually threaded or clipped into the inlet piping).
• 2. Inspect wiring: Check the sensor harness for cuts, abrasions, or loose connectors at both the sensor and control board. Reseat connectors firmly.
• 3. Test sensor resistance: With the sensor disconnected and the water at room temperature, measure resistance with a multimeter. Compare to Lochinvar's NTC chart. If the sensor reads open, shorted, or far out of range, replace it.
• 4. Clear error and test: After replacing or reconnecting the sensor, restore power and reset the control. If E006 returns and the sensor tests good, the control board input may be defective and should be evaluated by a technician.