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Takagi Water Heater, Geyser, Cylinder, Calorifier Contact Information

Takagi water heater error codes master list & Takagi water heater manuals.

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Takagi Water Heater Manuals, Troubleshooting Guides, Error Codes Contacts

Takagi produces these currently-popular tankless water heaters: T-KJr2/U, T-K4/U, T-D2/U, and the T-H3 series T-H3M-DV, T-H3J-DV, T-H3S-DV, T-H3-DV

Takagi Condensing Water Heater Error Codes

Universal Table of Takagi / A.O. Smith Condensing Water Heater Error Codes
Error Code Meaning Takagi Water
Heater Models
1 Wrong dip switch setting Red LED / Computer Board Fault  110 (T‐ KJr2), 310 (T‐K4) Remote
2

Inlet Thermistor / Output Thermistor / Air-fuel ratio rod failure
3 Ignition Failure / Flame Loss
4 Abnormal Fan Motor
5 Warning for 991 error code / Abnormal Combustion
6 Abnormal Gas Valves / Abnormal Solenoid Gas Valve / False Flame Detection
03 Wrong dip switch setting, 110 (T‐ KJr2), 310 (T‐K4) Remote 110 (T‐ KJr2), 310 (T‐K4) Remote
10 Warning for 991 Error Code
11 Ignition failure
12 Flame loss
31 Output Thermistor
32 Inlet Thermistor
39 Air-Fuel Ratio Rod Failure
51 Abnormal Gas Valves
55 Abnormal Solenoid Gas Valve
61 Abnormal Fan Motor
70 Computer board fault
72 False flame detection
74 Remote controller communication failure
99 Abnormal combustion

031

Wrong dip switch setting, possibly LP gas set when the fuel is Natural gas, or vice versa

T-D2, T-H2-OS

T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-M32, T-M50
070 Computer board failure - see 701  
072 False flame detected - see 721  
074 Remote control problem - see 741, 751  
099

Improper combustion - see 991

Watch out: this is an unsafe condition risking CO hazards.

 
101

Improper combustion.

Watch out: this is an unsafe condition. Look for a blocked flue or chimney (or downdrafts in the chimney) or a problem with the draft inducer fan.

Warning for 991 error code

T-D2, T-H2-OS

T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-M32, T-M50
111 Ignition failure; the burners do not light. Check for a bad igniter, flame sensor, gas valve. Check for gas supply. Check for a blown fuse on the circuit board.

T-D2, T-H2-OS, T-M32, T-M50
121 Burner flame lost. See code 111 above.
311 Output thermistor failure. Check the thermistor and its wires on the heat exchanger. Replace the thermistor if you don't see a loose or disconnected wire.

T-H2-OS

T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-M32, T-M50
321 Input / Inlet thermistor failure. Check the thermistor and its wires at the water inlet. Replace the thermistor if you don't see a loose or disconnected wire.
331 Mixing Thermistor failure
341 Thermistor failure , T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS
391 Air-fuel ratio rod failure. Check wire connections and if no loose wire, replace the AFR rod.

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-D2, T-M32, T-M50
441

Flow Sensor Failure (Easy-Link or Multi-Link System Only)

Possible: Inlet filter clogged, water flow problem. Also check for loose wire connections.

510 Gas valve failure. Inadequate gas pressure or flow.
551 Gas solenoid valve failure. Check gas supply and if no problem the solenoid needs replacement. T-H2-OS, T-M32, T-M50
611 Abnormal fan motor

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-D2, T-M32, T-M50
621 Exhaust fan motor (indoor models only) T-H2-OS
631 Pump Failure T-H2-OS, T-M32, T-M50
651 Flow Adjustment Valve Fault (Easy-Link or Multi-Link System only)

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-D2, T-M32, T-M50
661 Bypass valve fault (540 (T-H3) model only) T-H2-OS, T-M32, T-M50
681 External fan motor failure T-M50
701 Computer board failure; check for loose wires, electrical power supply, signs of damage to the board such as black or brown marks indicating overheating or burned

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-D2, T-M32, T-M50
711

High Limit Switch / Overheat Cutoff Fuse Circuit is Compromised

Watch out: this is an unsafe condition.

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS
721

False flame detected.

Check for condensate accumulation, blocked or missing condensate drain, condensate leaks.

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-D2, T-M32, T-M50
741 Remote control not communicating with the water heater, check remote batteries, check remote sensor wiring, remote control access line of sight.

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-M32, T-M50
751 Temperature Controller Problem T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS
761 Communication Error in Easy-Link or Multi-Link System.

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-D2, T-M32, T-M50
941

Abnormal exhaust temperature

Watch out: this is an unsafe condition risking CO hazards.

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS
991

Improper gas combustion. Abnormal combudstion.

Watch out: this is an unsafe condition risking CO hazards.
If this indicator is on from first activation of the heater it may not be properly adjusted for the elevation at which the heater is installed.

Check for blocked exhaust flue or under-sized exhaust flue.

Check for debris clogging the gas burner or for a failed or blocked fan.

T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS

T-D2, T-M32, T-M50

How to use this Takagi water heater error code table

Watch out: some water heater defects represent dangerous conditions, risking fire, explosion, or carbon monoxide poisoning or scalding hazards. Work on these heaters must be by a qualifed service professional.

All units are self diagnostic for safety and convenience when trouble shooting.

Error codes may be displayed in different locations, The 3‐digit 7‐Seg LED displays error code, or the TM‐RE30 (if installed) displays the 3‐digit error code, or for Easy-Link System units, The 7‐Seg LED of the individual unit with the error in question displays the whole 3‐digit error code.  

The TM‐RE30 (if installed) displays a 3‐digit number which signifies which unit has the error, and what the error code is.  

If there is a problem with the installation or the unit, it will display a numerical error code on the Remote Controller (if installed), on the 7‐Seg LED on the computer board (510 (T‐D2)), or
the flashing red LED (110 (T‐KJr2), 310 (T‐K4)) to communicate the source of the problem.  

Consult the chart for the cause of each error code.

If no your water heater model is not listed in the right-hand column then the error code on this table row may not apply.

See the water heater manual or troubleshooting manual for your specific water heater model for expanded detail about the meaning and the corrective steps for each of these error codes.

Also see AO SMITH WATER HEATER AGE & MANUALS where A.O. Smith water heater error codes are given.

Also see A.O. Smith CONDENSING WATER HEATER TROUBLESHOOTING GUIDE [PDF], (2011) A.O. Smith Water Products Company 500 Tennessee Waltz Parkway Ashland City, TN 37015 Toll Free: 1‐877‐737‐2840

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2019-06-23 by (mod) -

I've been surprised how quickly it's been necessary to clean some tankless water heaters. It's a good idea to flush it out make sure that the coil is not clogged and then reset the unit.

On 2019-06-23 by Barb

My Takagi has always worked great. Today it is in STANDBY mode. There is no hot water. It is 5 yrs old & I have not cleaned it every yr as instructed.
Should I do that first...and then reset it?
Thanks

On 2019-03-09 by Anonymous

Thank you

On 2019-03-08 by (mod) -

You can see #39 in the Takagi water heater error code table above

39 Air-Fuel Ratio Rod Failure

Sounds like a burner or combustion air adjustment issue

It's time for help from a Takagi-trained service technician on-site, for both function and for your safety.

On 2019-03-07 by Anonymous

Now I am getting error code 39 when the downstairs is tuned on while the upstairs was on and working.

On 2019-03-05 by (mod) -

Brad

Am I right that this is a variable flame capacity water heater? There may be an effect of flow rate demand on the heater that in turn controls flame height that in turn is not working properly.

For example with a Bosch variable flame water heater with which I've been experimenting across several models, with some models if the flow rate through the heater is insufficient the flame will go out.

Try a faster flow rate shower head in that downstairs shower and let me know if that fixes the trouble.

It's not literally pressure (though that's the word people commonly use) that is critical, it's water flow rate in gpm or lpm.

On 2019-03-05 by Brad

Thanks for the reply. If I turn the unit off and then on again, I can get the flame to stay lit. This seems to only be a problem when the downstairs shower is turned on. When the upstairs, or dishwasher are used, the flame stays lit.

Pressure issue with the water?
I have cleaned the filter and am now going to clean the rods.

On 2019-03-03 by (mod) -

Brad

As you saw in the Takagi water heater error codes in the table in this article, error 12 = a flame loss. That can be a problem with fuel, igniter, fuel valve, piping, burner adjustment, cleaning, combustion air supply etc.

Start with the troubleshooting advice in your Takagi manual,

also see GAS BURNER FLAME & NOISE DEFECTS https://inspectapedia.com/plumbing/Gas_Flame_Noise_Defects.php

keep me posted.

On 2019-03-03 by Brad

I get error code 12 on my TK-4 IN. I have cleaned the filter and it is still happening. Any thoughts?

On 2019-02-23 by (mod) -

Perhaps there is a scale clogging problem.

On 2019-02-23 by Marty Prevosto

My Takagi is inside the house when we go to use the shower an turn on the hot it rumbling an goes hot to cold hot to cold


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