Takagi Water Heater Error Codes — Meanings, Causes & Repair in Greater Vancouver

Seeing a fault code on your Takagi water heater? This guide explains what the most common Takagi water heater error codes mean, what’s safe to check yourself, and when to call HeatLand’s licensed, TSBC-certified gas technicians for Takagi water heater repair across Metro Vancouver and the Fraser Valley.

The codes below apply across common Takagi models (T-H3, T-D2, T-K4, T-KJr2). Meanings follow Takagi’s documented fault codes — always confirm against your unit’s own manual, because exact wording can vary by model, control board and firmware.

How to read Takagi water heater error codes

3-digit numeric error codes shown on the remote/temperature controller and/or as a code on the unit's PCB green LED on condensing models (e.g. T-H3/T-D2). On older non-condensing 110 (T-KJr2) and 310 (T-K4) units the same faults are shown as a 2-digit code plus a red-LED flash count (e.g. 510 'Abnormal Gas Valves' = code 51 / 6 flashes). Codes below use the standard 3-digit form.

Takagi water heater error codes & what they mean

These are the Takagi water heater codes our Greater Vancouver technicians see most. Anything marked pro repair involves gas, electrical, sealed-combustion or control-board work that must be done by a licensed gas technician (TSBC-certified in BC) — never open gas or electrical components yourself.

Code	What it usually means	Common causes	Safe to check yourself
031	Incorrect DIP switch setting (e.g. wrong gas type, venting, or Easy-Link master/slave setting on the computer board) pro repair	Gas-type DIP switch set incorrectly for the installed gas (NG vs LP); Venting-length or altitude DIP switches set wrong; Easy-Link master/slave DIP switch misconfigured on a multi-unit setup	Confirm the unit is being asked to do a normal task and try a single power-off / power-on reset; Note that DIP switch changes are inside the unit and must be done by a licensed technician
101	Warning for the 991 (abnormal/imperfect combustion) error code; gas input is reduced as a protective measure pro repair	Blockage or restriction in the intake-air or exhaust venting; Dirt, grease or lint in the burner, fan motor or heat exchanger (often a contaminated install area); Incorrect altitude/elevation DIP switch setting for the location	Visually check that outdoor intake and exhaust vent terminals are clear of snow, leaves, lint or debris; Make sure the area around the unit is clean and not dusty/lint-heavy; Try a single power-off / power-on reset after confirming vents are clear
111	Ignition failure (the heater did not light after its ignition attempts) pro repair	Gas supply off, low gas pressure, or undersized/faulty gas regulator at the meter; Air in the gas line after service; Faulty igniter, flame rod, gas valve assembly or computer board	Confirm the gas is turned on and the gas meter/cylinder is not empty; Check that another gas appliance in the home lights normally (rules out a whole-home gas-supply issue); Try a single power-off / power-on reset
121	Loss of flame / flame loss (flame went out while the unit was supposed to keep running) pro repair	Faulty gas pressure regulator at the meter or fluctuating gas supply; Sooted or dirty flame rod, or wiring break to the flame rod; Damaged overheat cut-off fuse, heat-exchanger leak, gas valve or computer board fault	Confirm the gas is on and other gas appliances work normally; Check outdoor vent terminals are clear; Try a single power-off / power-on reset
311	Outlet (output) thermistor fault – disconnected or short-circuited outlet temperature sensor pro repair	Loose, corroded or broken wiring at the outlet thermistor; Debris or scale on the thermistor probe; Failed outlet thermistor	Try a single power-off / power-on reset; No homeowner-serviceable thermistor checks – the sensor is inside the unit
321	Inlet thermistor fault – disconnected or short-circuited inlet (incoming water) temperature sensor pro repair	Loose, corroded or broken wiring at the inlet thermistor; Debris or scale on the thermistor probe; Failed inlet thermistor	Try a single power-off / power-on reset; No homeowner-serviceable thermistor checks – the sensor is inside the unit
331	Mixing thermistor fault – disconnected or short-circuited mixing temperature sensor pro repair	Loose, corroded or broken wiring at the mixing thermistor; Debris or scale on the thermistor probe; Failed mixing thermistor	Try a single power-off / power-on reset; No homeowner-serviceable thermistor checks – the sensor is inside the unit
341	Disconnected/short-circuited thermistor (heat-exchanger thermistor group); on the T-H3 the 341 code applies to the 540 (T-H3) models pro repair	Loose, corroded or broken thermistor wiring; Debris on the thermistor probe; Failed thermistor	Try a single power-off / power-on reset; No homeowner-serviceable thermistor checks – the sensor is inside the unit
391	Air-fuel ratio rod failure (the rod used to monitor the air/fuel ratio is faulty) pro repair	Broken or disconnected air-fuel ratio rod wiring; Soot build-up on the flame/air-fuel ratio rod; Failed exhaust thermistor or rod	Confirm outdoor vent terminals are clear of debris; Try a single power-off / power-on reset
441	Flow sensor failure (Easy-Link multi-unit system only) pro repair	Debris on the flow-sensor impeller; Broken or disconnected flow-sensor wiring; Failed flow sensor	Confirm the building water supply is on and water is flowing to the unit; Try a single power-off / power-on reset
510	Abnormal main gas solenoid valve / abnormal gas valves pro repair	Faulty or stuck gas valve assembly / main gas solenoid valve; Broken or disconnected gas-valve wiring; Computer board fault driving the gas valves	Confirm the gas is on and other gas appliances work normally; Try a single power-off / power-on reset (do not open the gas valve assembly)
551	Abnormal gas solenoid valve (secondary solenoid gas valve fault) pro repair	Faulty or stuck solenoid gas valve; Broken or disconnected valve wiring; Computer board fault driving the solenoid valve	Confirm the gas is on and other gas appliances work normally; Try a single power-off / power-on reset (do not open the gas valve assembly)
611	Fan motor fault / abnormal fan motor pro repair	Broken, frozen or corroded wiring/connectors at the fan motor; Dust build-up or obstruction in the fan motor; Failed fan motor	Confirm outdoor intake/exhaust terminals are clear of debris or ice; Try a single power-off / power-on reset
651	Flow adjustment valve fault (Easy-Link system only) pro repair	Broken or disconnected flow-adjustment-valve wiring; Stuck flow adjustment valve (e.g. scale build-up); Failed flow adjustment valve	Confirm the building water supply is on and water is flowing; Try a single power-off / power-on reset
661	Bypass valve fault pro repair	Broken or disconnected bypass-valve wiring; Bypass valve drive locked by scale build-up; Water leakage at, or failure of, the bypass valve	Confirm the building water supply is on; Try a single power-off / power-on reset
701	Computer board (PCB) fault – includes proportional gas valve drive fault pro repair	Failed computer board (PCB); Proportional gas valve or its wiring fault; Electrical surge or moisture damage to the board	Try a single power-off / power-on reset; No homeowner-serviceable parts – board service is internal/electrical
711	Gas solenoid valve drive circuit failure (on the T-H3 this also relates to the high-limit switch / overheat cut-off fuse circuit being compromised) pro repair	Open or compromised high-limit switch / overheat cut-off fuse circuit (often after an overheat event); Gas solenoid valve drive circuit fault on the computer board; Broken wiring in the solenoid/high-limit circuit	Confirm outdoor vent terminals are clear and the inlet water filter is not blocked (overheating is often flow/venting related); Try a single power-off / power-on reset
721	False flame detection (the unit detects a flame when there should be none) pro repair	Sooted or contaminated flame rod; Heat-exchanger leak affecting the flame rod; Wiring or computer board fault	Try a single power-off / power-on reset; No homeowner-serviceable flame-rod checks – the rod is inside the burner
741	Miscommunication between the water heater and the remote (temperature) controller pro repair	Broken, loose or miswired remote-controller communication wiring; Computer board fault; Failed remote controller	Confirm the remote controller's power button is on; Try a single power-off / power-on reset
751	Miscommunication between the water heater and the temperature controller pro repair	Broken, loose or miswired controller communication wiring; Computer board fault; Failed temperature controller	Confirm the controller's power button is on; Try a single power-off / power-on reset
761	Communication failure between the parent (master) unit and a child (slave) unit in an Easy-Link multi-unit system pro repair	Incorrect or loose communication cabling between linked units; Power lost to one of the linked units; DIP switch / master-slave misconfiguration	Confirm every linked unit has power; Try a single power-off / power-on reset of the system
941	Abnormal exhaust temperature pro repair	Broken or disconnected wiring / dust build-up in the fan motor; Burn marks or fault on the computer board; Exhaust/heat-exchanger restriction	Confirm exhaust vent terminals are clear of any obstruction; Try a single power-off / power-on reset
991	Imperfect / abnormal combustion pro repair	Blocked or restricted intake-air or exhaust venting; Dirt/grease/lint in the burner, fan or heat exchanger; Incorrect altitude or gas-type DIP switch settings	Check that outdoor intake and exhaust vent terminals are clear of debris; Make sure the area around the unit is clean and well-ventilated; Try a single power-off / power-on reset

Takagi water heater codes we get called for most

111 — Ignition failure (the heater did not light after its ignition attempts)

Typical causes include gas supply off, low gas pressure, or undersized/faulty gas regulator at the meter; air in the gas line after service; faulty igniter, flame rod, gas valve assembly or computer board. A few things are safe to check yourself (Confirm the gas is turned on and the gas meter/cylinder is not empty; Check that another gas appliance in the home lights normally (rules out a whole-home gas-supply issue)), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 111 on Takagi water heaters throughout Greater Vancouver.

121 — Loss of flame / flame loss (flame went out while the unit was supposed to keep running)

Typical causes include faulty gas pressure regulator at the meter or fluctuating gas supply; sooted or dirty flame rod, or wiring break to the flame rod; damaged overheat cut-off fuse, heat-exchanger leak, gas valve or computer board fault. A few things are safe to check yourself (Confirm the gas is on and other gas appliances work normally; Check outdoor vent terminals are clear), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 121 on Takagi water heaters throughout Greater Vancouver.

711 — Gas solenoid valve drive circuit failure (on the T-H3 this also relates to the high-limit switch / overheat cut-off fuse circuit being compromised)

Typical causes include open or compromised high-limit switch / overheat cut-off fuse circuit (often after an overheat event); gas solenoid valve drive circuit fault on the computer board; broken wiring in the solenoid/high-limit circuit. A few things are safe to check yourself (Confirm outdoor vent terminals are clear and the inlet water filter is not blocked (overheating is often flow/venting related); Try a single power-off / power-on reset), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 711 on Takagi water heaters throughout Greater Vancouver.

611 — Fan motor fault / abnormal fan motor

Typical causes include broken, frozen or corroded wiring/connectors at the fan motor; dust build-up or obstruction in the fan motor; failed fan motor. A few things are safe to check yourself (Confirm outdoor intake/exhaust terminals are clear of debris or ice; Try a single power-off / power-on reset), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 611 on Takagi water heaters throughout Greater Vancouver.

Is it safe to keep running a Takagi water heater with a fault code?

Most Takagi fault codes put the water heater into a safe lockout for a reason. You can safely check the basics — the gas supply on, the pilot light or igniter, the temperature dial setting, the breaker on (power-vent/electric/hybrid models), and no water leaking around the tank — and restart it once. If the code returns, stop and book a technician. If you smell gas, leave the building and call your gas utility’s emergency line or 911 first. If a carbon-monoxide alarm sounds, get everyone out and call 911. Never cap or block the temperature & pressure (T&P) relief valve, and don’t keep relighting a pilot that won’t stay lit.

Takagi water heater repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair Takagi water heaters — pilot and ignition faults, gas-control (status-light) codes, sensor and thermostat errors, vent and air-intake blockages, leak shut-offs, and (on hybrid/heat-pump and tankless models) control-board and component faults — including units we didn’t install. We’re brand-agnostic, carry common parts, and give you an honest repair-or-replace assessment with upfront pricing and a free estimate. If your water heater is beyond economical repair, we’ll show you right-sized, high-efficiency replacement options and the rebates available.

Need it sorted fast? We offer priority emergency water heater repair. Explore Water Heater services, browse all water heater error codes by brand, or request a free estimate.

Takagi water heater service areas

We repair Takagi water heaters across Greater Vancouver and the Fraser Valley, including:

Takagi water heater error code FAQs

Can I reset my Takagi water heater myself?

Yes — power-cycling the reset button once is generally safe after you’ve checked the basics (the gas supply on, the pilot light or igniter, the temperature dial setting, the breaker on (power-vent/electric/hybrid models), and no water leaking around the tank). If the water heater faults again right away, stop and note the code — repeatedly resetting a water heater that keeps locking out can mask a real problem. Call a licensed, TSBC-certified gas technician to diagnose it.

What does the Takagi 111 code mean?

On Takagi water heaters, 111 commonly indicates ignition failure (the heater did not light after its ignition attempts). Confirm the exact meaning against your unit’s manual — codes can vary by model and series — and have the repair done by a licensed, TSBC-certified gas technician. HeatLand fixes this across Greater Vancouver.

Do you repair Takagi water heaters you didn’t install?

Yes. HeatLand is brand-agnostic and services Takagi water heaters throughout Metro Vancouver and the Fraser Valley, whether or not we installed the unit. We carry common parts and give you an honest repair-or-replace assessment.

Is a Takagi water heater fault code an emergency?

No heat in cold weather is worth treating urgently. If you smell gas, leave the building and call your gas utility’s emergency line or 911 first. If a carbon-monoxide alarm sounds, get everyone out and call 911. Never cap or block the temperature & pressure (T&P) relief valve, and don’t keep relighting a pilot that won’t stay lit. For priority water heater repair across Greater Vancouver, call (604) 330-3812.

How much does Takagi water heater repair cost in Vancouver?

It depends on the fault. Many Takagi codes point to sensors, ignition or pump parts — usually far cheaper than replacement. We give upfront pricing and a free estimate before any work.

More Water Heater error-code guides

HeatLand repairs every major water heater brand across Greater Vancouver. More brand guides: