Eccotemp Error Codes: i12 E0 to E8 Explained

By Ray Bennett · Updated 23 October 2026 · 6 min read · Checked against the maker’s manual

Eccotemp Error Codes: i12 E0 to E8 Explained

Short answer

Eccotemp's i12 manual lists E1 as ignition failure, E3 as overheat protection and E8 as a blocked vent pipe. Record the full code and confirm i12-LP or i12-NG before using its chart. Gas, vent, sensor and electrical repairs belong to qualified service; overheating or a gas smell comes before any restart.

Eccotemp error codes belong to a particular water heater. In the i12-LP/NG manual, Printing Version 2.0, E1 is ignition-system failure, E3 is overheat protection and E8 is a blocked vent pipe. The number describes a fault condition; it does not select a replacement part.

This page follows that i12 chart, including E0 through E8. Check the model and manual before applying it to another Eccotemp series. Start by photographing the display, then keep any gas smell, overheating or damage ahead of a restart.

The tankless water heater code guide helps identify other brands. For a symptom without a display message, use the tankless water heater troubleshooting guide while keeping the i12’s instructions beside you.

Before you start

What to carry: a torch, a phone and the matching manual. Read an accessible model label or installation paperwork without removing the cover. Record the exact code, whether any tap produced hot water and what happened before the fault.

Gas or electric? The i12-LP and i12-NG covered here are gas tankless water heaters with an electrical supply. Eccotemp’s manual distinguishes LP and natural gas models. Do not treat a powered display as proof that the gas supply, ignition or venting is correct.

Renting? Send maintenance the model, code and whether the problem affects every hot tap. Include any recent supply interruption or restart already attempted.

A gas smell or overheating takes priority over the code chart.
Eccotemp says that if you smell gas, do not try to light an appliance, touch an electrical switch or use a phone inside the building. Leave and call the gas supplier from a neighbor’s phone. If the supplier cannot be reached, call the fire department.

Eccotemp requires shutting the manual gas control valve if the heater overheats, its gas supply fails to shut off, or it has suffered fire, flooding or physical damage. Only approach the valve if safe. Leave the heater off and arrange qualified service before restarting.

The i12 manual says not to disassemble the unit for any reason. It reserves electrical wiring, gas piping, burners, vent connectors and safety-device repairs for qualified service. Keep the cover fitted and do not bypass a switch or sensor.

Eccotemp also warns that water above 120 F can cause severe scalding or death. A hotter setting is not a general repair for an error message. Keep people away from unexpectedly hot water and arrange service for the cause.

Match the i12 code to the manual

Check 1A model-specific code lookup and a useful service record

Record the full message before changing anything

Eccotemp’s printed page 35 gives these descriptions. The possible causes in that table remain possibilities, not confirmed defects.

Code	Eccotemp i12 description	Repair boundary
E0	Hot-water sensor failure	Qualified sensor and connection diagnosis
E1	Ignition-system failure	Record known supply status; leave ignition and gas testing to service
E2	Flame when no water is coming in	Service for the listed circuit problem
E3	Overheating protection	Overheat response and professional diagnosis
E4	Cold-water temperature sensor	Sensor, connector and control diagnosis
E5	Pressure switch	Qualified motor, supply-voltage and safety-circuit checks
E6	Overheating	Professional review of the listed gas, water and control conditions
E7	Solenoid valve	Valve-circuit diagnosis and any replacement
E8	Vent pipe blocked	Qualified vent inspection and correction

An unlisted code has a separate instruction. Eccotemp says to turn off the hot-water faucet, note the message, switch off the remote control and call customer assistance. Do not borrow a meaning from a portable heater or another i12 revision.

In Eccotemp's i12 chart, E1, E3/E6 and E8 identify different fault conditions. None authorizes opening the case or repairing a gas or vent component yourself.

E1: establish the supply history without opening the heater

Check 2Outside observations for the service technician

Separate a failed ignition from a proven bad part

For E1, Eccotemp lists a gas valve not open fully, a water shut-off valve not open and a loose junction connection. That list does not prove an igniter or computer board has failed.

Report a known gas interruption, closed supply valve or loss of water pressure. If you do not know the supply status, say so. Do not loosen a gas fitting, take a pressure reading inside the unit or open the cabinet to inspect the listed connection.

Eccotemp’s operating section says the i12 is flow activated and needs at least 0.6 GPM to activate and remain activated. Its no-hot-water table also names an incompletely opened hot faucet as a possible cause.

Record whether the problem appears at one fixture or every fixture, and whether the display changes with normal hot-water use. This is information for diagnosis, not proof that a flow sensor needs replacement. Leave internal strainers, sensors and plumbing disassembly to service in this guide.

E3, E5, E6 and E8 need the correct safety response

Check 3Shutdown when necessary, then qualified fault diagnosis

Keep overheat and vent faults out of a repeated restart loop

Eccotemp’s E3 row lists dry combustion or an overheat-controller problem. Its E6 row lists high gas pressure, a water valve not fully open or a temperature setting too low. Those are the manual’s possible causes, not instructions to adjust gas pressure yourself.

Although the E6 row includes increasing the setting among its corrective actions, the same manual warns about scalding and requires the gas valve to be shut for overheating. Leave selection of an appropriate correction to qualified service. Do not raise the setting blindly to clear E6.

For E5, the table names a motor problem or low supply voltage. For E8, it identifies a blocked vent pipe. Eccotemp explicitly reserves vent-connector and safety-device repair for qualified personnel.

From a safe ground-level position, report a visible vent obstruction or damage. Do not climb, pull a vent joint apart or run the heater with the pipe disconnected. A code that disappears after a restart does not establish that a vent or supply fault has been repaired.

What the i12 manual says about trying again

Check 4The manual's waiting period, followed by service if the fault remains

Use only the applicable code-guide sequence

For a listed code, Eccotemp’s guide begins by closing the hot-water faucet. It says to wait five minutes before turning the unit on again, then open the hot-water faucet. The gas-smell, overheating and damage instructions above take priority.

If the code remains, Eccotemp says to close the faucet and take the appropriate action from its table. The internal and gas-related actions in that table belong to service here. Do not turn that instruction into permission for owner disassembly.

If the code is still shown, its final instruction is to turn off the hot-water faucet, record the display and call customer service. Keep the original message and the attempted sequence available for the technician.

Eccotemp’s separate troubleshooting table says the fan can continue for 10 to 15 seconds after the hot faucet closes to purge unburned gas. It calls that normal operation and says to check for a code. A short fan run alone is not an E5 diagnosis.

Eccotemp's i12 code guide gives a five-minute wait for its listed-code sequence. Gas smell, overheating and damage take priority; persistent or unlisted codes go to service.

What each one takes

Finding	Work involved
E1	Supply, water-flow and ignition diagnosis
E0 or E4	Sensor and connection testing by service
E3 or E6	Safe shutdown for overheating and qualified diagnosis
E5 or E7	Electrical, motor or valve-circuit service
E8	Vent inspection and correction by qualified personnel

Questions people ask

Where is the Eccotemp i12 error code manual?

Eccotemp’s official i12-LP/NG manual page supplies the PDF. This article follows the 2022 Printing Version 2.0 chart on printed page 35.

Does E1 prove the igniter is broken?

No. Eccotemp’s i12 chart lists several possible supply and connection conditions. Confirm the cause through qualified diagnosis before choosing a part.

Are E3 and E6 both overheating codes?

The i12 table calls E3 overheating protection and E6 overheating, with different possible causes. Both keep the manual’s overheating safety instruction ahead of a restart.

Should I clean the vent myself for E8?

Eccotemp identifies vent blockage but reserves vent-connector and safety-device repairs for qualified personnel. Leave the vent assembled and arrange service.

Does this chart cover portable Eccotemp models?

No. It is scoped to the named i12-LP/NG manual. Use the exact portable model’s instructions instead.

For other symptoms, see tankless water heater problems; for another brand’s display, use the brand code index.

Sources: Eccotemp i12 LP/NG Installation, Use and Care Instructions, copyright 2022, Printing Version 2.0, printed pages 2, 28 to 30 and 33 to 35. Official PDF saved from Eccotemp support. Image-only source pages visually checked and quoted in a separate verbatim transcript.