Troubleshooting A "0" And "4" Error Code On A Fogatti Tankless Water Heater

Updated 06/30/2025 | Published 09/15/2023

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Digital Multimeter with 42" Long Test Leads - LED Display

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Question:

Fogatti Tankless Water Heater EC Error Code TroubleShoot Mine shut down. Pulled fuse for 15 minutes. When we turn the switch on at the panel to put power to heater the remote turns on flashes all 0s the an alone 4 and turns off. What might be the problem? Not this is not a installation. The unit has been in for around 6 months.

asked by: Jim W

Expert Reply:

A "0" error code means that your outlet temperature probe is open or shorted and a "4" error code means that your inlet temperature probe is faulty and the inlet temperature probe is open or shorted. I recommend checking that your Fogatti RV Tankless Water Heater # LSB44FR is getting a full 12 volts of power at the unit with a multimeter # PT89ZR and that it has a proper ground connection. If both the power and ground are fine then you'll need to reach out to the manufacturer for replacement sensors.

expert reply by: Kevin C

Outlet temp probe
(click to enlarge)

Jorge

12/23/2024

Im having an issue where when I switch the power on in the RV, the Hater heater control panel/remote displays just ine 0 before turning off. It wont allow me to start my water heater.

Kevin C.

12/26/2024

@Jorge The "0" error you're seeing is saying that your outlet temperature probe is faulty and not able to read the temperature for the outgoing water. To avoid accidentally running the water to hot and burning anyone the unit is shutting itself down. I've attached a diagram below to show you where the probe sits inside of the unit, but you'll need to reach out to LaSalle Bristol for a replacement probe.

Carol R.

6/28/2025

I replaced a tankless RV of the same model with a brand new but did not switch out the wire controller but I am still getting the same “4” code, there is no E not a 0 in front of the “4.” What do you think could be the problem?

Jon G.

6/30/2025

@CarolR If you got a brand new unit and it's still saying that the inlet temperature probe is faulty (open or shorted) then the problem might be the controller. Have you looked at the inlet temp probe on your new unit to make sure it's in good shape?