EcoSmart Eco 22 Error Codes - Causes & Fix

EcoSmart Eco 22 Error Codes — What It Means

The EcoSmart Eco 22 tankless electric water heater displays five main error codes. E1 indicates a fault with the inlet thermistor (incoming-water temperature sensor), E2 signals a fault with the outlet thermistor (outgoing-water temperature sensor), and E3 means both thermistors or the broader temperature-sensing circuit are affected. E4 appears when incoming water temperature exceeds 140°F, which is above the safe operating limit. E5 means the unit is seeing excessive flow rate beyond what it can heat properly.

These codes stop operation to protect the heater and prevent unsafe conditions. Most faults involve either a failed sensor, incorrect wiring connection, or a plumbing condition outside the heater itself. The unit will not resume normal operation until you address the root cause and clear the fault.

Jump to Fix

Common Causes

• Failed inlet or outlet thermistor The temperature sensor itself has failed internally and no longer provides accurate readings to the control board.
• Loose or corroded sensor wiring The thermistor connector or wiring harness has come loose, corroded, or sustained damage that interrupts the signal.
• Incoming water temperature too high Supply water entering the unit is already above 140°F, often due to a mixing valve or tempering arrangement feeding preheated water back into the heater inlet.
• Flow rate exceeding heater capacity Too many fixtures are drawing simultaneously or a single fixture is flowing at a rate the unit cannot heat, triggering the E5 over-flow fault.
• Control board or sensor circuit fault The main control board has a fault in the thermistor circuit or power supply that prevents normal sensor operation.

Step-by-Step Fix {#fix}

1. Verify the displayed code and note whether it is E1, E2, E3, E4, or E5 by reading the digital display on the front of the unit.
2. For E1, E2, or E3 faults, turn off power at the breaker and inspect both thermistor connectors and wiring for looseness, corrosion, or visible damage. Reconnect any loose plugs and clean corroded contacts with electrical contact cleaner.
3. Perform the temporary reset test by restoring power, running a hot-water faucet, then holding the round temperature knob for 3 to 5 seconds until the display shows CE1 or CE2. Observe whether hot water is restored for 2 to 3 minutes. If the fault returns, replace the affected thermistor.
4. For E4 faults, measure incoming supply water temperature with a thermometer at the inlet shutoff valve. If it exceeds 140°F, trace back to any mixing or tempering valve feeding hot water into the unit and correct the plumbing arrangement so only cold supply water enters the heater.
5. For E5 faults, reduce flow demand by closing fixtures or partially closing the inlet shutoff valve until flow is within the heater’s rated capacity. Re-test with a single fixture at moderate flow and confirm the code clears and outlet temperature stabilizes.
6. After any repair, restore full power, clear the fault by cycling the breaker, and run a sustained hot-water draw test for at least five minutes to confirm stable operation without code recurrence.
7. If the fault persists after sensor replacement, wiring repair, or flow correction, test the control board or consult the manufacturer’s service data for circuit resistance values and advanced diagnostics.

Parts Often Needed

When to Call a Pro

Call a licensed electrician or water heater technician if you are not comfortable working inside a 240V appliance, if sensor replacement does not clear E1, E2, or E3 codes, or if E4 faults persist after verifying incoming supply temperature. A professional should also diagnose E5 faults when flow reduction does not resolve the issue, as this may indicate a control board failure or incorrect initial sizing. Any situation involving repeated fault codes after multiple repairs requires advanced circuit testing and manufacturer service data that most homeowners do not have access to.