How to Fix / Troubleshooting

Safety: Turn off power and allow the tank to cool before removing any sensor wells.

Steps:

1. Locate tank sensor: On storage-type Lochinvar heaters, the tank sensor is typically inserted into a well on the side of the tank.
2. Check seating: Ensure the sensor is fully inserted into the well and secured. A partially inserted sensor can give false readings.
3. Test sensor: Disconnect the sensor and measure resistance. Compare to Lochinvar's thermistor chart. Replace the tank sensor if readings are not within specification.
4. Inspect wiring: Check the harness from the tank sensor to the control for damage or loose connectors.
5. If problem persists: If a new sensor does not resolve E008, the control board may have a failed sensor input and should be replaced by a qualified technician.

Control displays E008 and unit locks out; may be accompanied by erratic temperature readings.

Possible Causes