Westinghouse Water Heater Error Codes

Common Symptoms

• WV8840 LED blinking repeatedly on gas storage model — count the flashes before the pause
• Error 11, 12, 14, 16, 30, or 90 on condensing tankless display panel
• No hot water with no visible error code — electric model ECO has tripped
• Unit fires briefly then shuts off — flame loss (Error 12) or ECO trip (blink 4)
• Gradually worsening hot water output — Error 90 scale developing
• Unit locks out and requires power cycle to restart

Most Likely Causes

1. 1

   WV8840 Blink Code 1 — Standby or Thermopile Low Voltage (<350 mV)

   One blink (single flash, pause, repeat) from the WV8840 status LED indicates the unit is in standby with the pilot lit, or that thermopile voltage is borderline low. If the pilot just lit, wait 60 seconds for the thermopile to warm to full output voltage — 1 blink during warmup is normal. If blink code 1 persists beyond 2 minutes with the pilot burning steadily, test thermopile millivoltage: connect a millivolt DC meter to the TH and TH/TP terminals. Reading below 350 mV confirms low thermopile output. A clean, full pilot flame should bring output to 600–850 mV — if not, the thermopile is failing.

2. 2

   WV8840 Blink Code 2 — Thermopile Below 350 mV (Replace Thermopile)

   Two blinks confirms the thermopile is generating insufficient voltage to keep the WV8840 main gas valve open — the valve requires a minimum of 350 mV from the thermopile circuit to energize. Replace the thermopile: Westinghouse WR49X10173 and AO Smith 9005502 are the same part and both fit WGRN/WGRD models. The thermopile screws out of the pilot assembly and connects via two spade terminals. After replacement, verify millivoltage is 600–850 mV with the pilot burning for 3–4 minutes before concluding the replacement was successful.

3. 3

   WV8840 Blink Code 3 — Gas Valve Fault (Gas Supply Issue or Valve Failure)

   Three blinks means the WV8840 is receiving an open command but is detecting a valve circuit fault — either no gas is reaching the valve or the valve itself is malfunctioning. Check: is the manual gas shutoff at the unit fully open? Is gas available at other appliances? Is the inlet gas pressure within the acceptable range (NG: 4–10.5 in. w.c., LP: 8–14 in. w.c.)? If all gas supply checks pass, the WV8840 valve is internally faulty and must be replaced by a licensed gas technician.

4. 4

   WV8840 Blink Code 4 — ECO / High-Limit Trip (Reset ECO Button)

   Four blinks indicates the ECO (Energy Cut-Off) thermostat or high-limit device has tripped — the safety cutoff activated because water temperature exceeded the design limit. Press the red ECO reset button behind the thermostat access panel. If the unit trips again immediately or within 30 minutes, the thermostat is calling for excessive temperature or the gas valve is sticking open — both require a technician. Always check that the thermostat is set to 120°F (49°C) or below before resetting the ECO.

5. 5

   WV8840 Blink Code 7 — Thermal Switch or Gas Valve Failure

   Seven blinks indicates either the thermal switch near the flue collar has tripped (an overtemperature safety device for the draft hood area) or the gas valve has failed. Locate the thermal switch — a small round disc or button device with two wires, positioned near the flue collar or draft hood — and press to reset. If blink code 7 clears after reset and does not return, the thermal switch was the cause. If the code returns or the reset does not affect the blink pattern, the WV8840 gas valve must be replaced by a licensed technician.

6. 6

   Condensing Tankless Error 11 — No Ignition (Gas Supply, Igniter Electrode)

   Error 11 on WGRTLP and WGRTNG condensing tankless units means the ignition sequence completed but the flame sensor detected no flame. Primary causes: gas supply valve not fully open, gas pressure out of spec (NG: 3.5–10.5 in. w.c.; LP: 8–14 in. w.c.), fouled or cracked igniter electrode, or failed igniter. Remove the burner access cover and visually inspect the igniter electrode tip for cracking or carbon deposit. Clean gently with a dry cloth. Restore gas, power cycle the unit (unplug 30 seconds), and retest. If Error 11 persists after electrode cleaning and gas supply confirmation, the igniter or gas valve must be replaced.

7. 7

   Condensing Tankless Error 12 — Flame Loss During Operation

   Error 12 means the unit ignited successfully but the flame sensor detected flame loss mid-cycle — the burner lit and then went out. Causes: gas supply pressure drop during demand (gas meter regulator issue or competing appliances), partially fouled flame sensor, or combustion air/vent obstruction causing unstable flame. Inspect the vent termination for partial blockage (bird nest, debris, frost). Check whether Error 12 occurs only during high-demand periods (possible gas pressure drop). Clean the flame sensor rod gently with a dry cloth.

8. 8

   Condensing Tankless Error 14 — Thermal Fuse (Descale FIRST)

   Error 14 indicates the thermal fuse has opened — a one-time safety device that trips when the heat exchanger temperature exceeds its rated limit, almost always caused by Error 90 scale buildup. The thermal fuse cannot be reset; it must be replaced. Critical: descale the heat exchanger FIRST before replacing the thermal fuse. Installing a new thermal fuse on a scaled heat exchanger will result in immediate re-trip on the first firing cycle. Perform the full descale procedure (CLR or white vinegar circulated for 45–60 minutes), then replace the thermal fuse.

9. 9

   Condensing Tankless Error 16 — Outlet Overtemperature

   Error 16 means the outlet water thermistor has detected water temperature above the maximum setpoint (typically 185°F/85°C). Causes: thermostat set too high (check remote controller setpoint), scale insulating the heat exchanger causing localized overheating (descale), or a failed thermistor reading low while actual temperature is high. If the setpoint is within range and Error 16 persists, perform a descale and test the outlet thermistor resistance against the manufacturer's resistance-temperature table.

10. 10

    Condensing Tankless Error 30 — Exhaust / Vent Blockage

    Error 30 indicates the exhaust pressure sensor has detected insufficient flue draft or a blocked vent. Inspect the vent termination (outdoor cap or indoor vent termination) for obstruction — frost, debris, bird or insect nest. Verify the vent run length and number of elbows does not exceed the maximum allowed in the installation manual. On concentric vent systems, verify the inner (exhaust) and outer (combustion air) tubes are not cross-contaminated. If no obstruction is found, the exhaust pressure sensor may be faulty.

11. 11

    Condensing Tankless Error 90 — Combustion Abnormality (Scale — Descale with CLR)

    Error 90 is the most common error code on WGRTLP and WGRTNG units in hard water areas — scale buildup on the primary heat exchanger reduces heat transfer efficiency, causing combustion abnormality as the burner overworks. Perform a full descale immediately: isolate the unit via cold inlet and hot outlet isolation valves, connect a submersible pump and hoses to the service port connections, circulate undiluted CLR or white vinegar for 45–60 minutes, flush with clean water for 15 minutes, restore isolation valves, power cycle. If Error 90 returns within weeks of descaling, the heat exchanger may be perforated and require replacement.

12. 12

    Electric Models (WECM, WECS) — No Display, ECO Reset + Element Resistance Test

    WECM and WECS electric storage water heaters have no error code display. Diagnosis is by ECO reset and element testing. Step 1: Turn off the 240V breaker. Remove the upper access panel and insulation. Press the red ECO reset button firmly until it clicks. Restore power and wait 30 minutes. If no heat: Step 2: Turn off the breaker again. Access both upper and lower elements through their respective panels. Disconnect element leads and test resistance with a multimeter — healthy range is 12–16 Ω. Open (OL) reading = failed element. Replace with Camco 02162 kit. Both elements can be tested without draining; draining is only required for removal.

Quick DIY Checks

1. 1Step 1 — Identify your model and fault communication method: Gas storage (WGRN, WGRD) = WV8840 LED blink codes. Condensing tankless (WGRTLP, WGRTNG) = numeric error codes on display or remote controller. Electric storage (WECM, WECS) = no display — proceed to ECO reset and element test.
2. 2Step 2 (Gas storage — WV8840 blink codes): Count the flashes before the pause on the gas valve status LED. 1 blink = standby/thermopile warming up (wait 2 minutes; if persistent, test millivoltage). 2 blinks = thermopile <350 mV (test millivoltage, replace thermopile WR49X10173/9005502). 3 blinks = gas valve fault (check gas supply). 4 blinks = ECO trip (press ECO reset button, verify thermostat ≤120°F). 7 blinks = thermal switch near flue collar (press reset) or gas valve failure.
3. 3Step 3 (Gas storage — thermopile millivolt test): Set multimeter to millivolts DC. Light the pilot and wait 3–4 minutes. Connect probes to the TH and TH/TP terminals on the WV8840 face. Healthy: 600–850 mV. Minimum to open the valve: 350 mV. Below 350 mV after 4 minutes with a steady pilot = replace thermopile. Use AO Smith 9005502 or Westinghouse WR49X10173 — both are the same part.

1. 4Step 4 (Gas storage — ECO reset for blink code 4): Turn off gas at the manual valve. Remove the thermostat access panel (two Phillips screws). Press the red ECO reset button firmly until you feel a click. Replace the panel. Re-light the pilot per the label instructions. If the ECO trips again within 30 minutes, call a technician — the thermostat or gas valve is malfunctioning.
2. 5Step 5 (Condensing tankless — Error 90): Immediately perform a descale. Connect a submersible pump and hoses to the cold inlet and hot outlet service ports (close the cold inlet and hot outlet isolation valves). Circulate undiluted CLR or white vinegar for 45–60 minutes. Flush with clean water for 15 minutes. Restore isolation valves. Power cycle (unplug 30 seconds). Check for recurrence — if Error 90 returns within a few weeks, the heat exchanger is damaged.
3. 6Step 6 (Condensing tankless — Error 14): Do NOT replace the thermal fuse before descaling. Error 14 almost always follows unresolved Error 90. Descale first (Step 5), then replace the thermal fuse. A new thermal fuse on a scaled heat exchanger will trip immediately.
4. 7Step 7 (Electric storage — WECM/WECS): Turn off 240V breaker. Remove upper access panel. Press red ECO reset button. Restore power. Wait 30 minutes. If still no heat, turn off breaker again, access both element panels, disconnect element leads, test resistance (12–16 Ω healthy; OL = failed). Replace failed element with Camco 02162 kit.
5. 8Step 8 — Power cycle reset procedure (all platforms): Unplug the unit or turn off the breaker for 30 seconds. Restore power. This clears soft error states and allows the control board to re-initialize. Always perform a power cycle after any repair before evaluating whether the error has been resolved.

Repair vs Replace

Recommended Tools & Parts

• Westinghouse / AO Smith Thermopile WR49X10173 (AO Smith 9005502)

  OEM-equivalent thermopile for WGRN and WGRD gas storage models — the replacement for WV8840 blink code 2 (thermopile <350 mV). Westinghouse WR49X10173 and AO Smith 9005502 are the same part. Includes spade connectors. Verified 600–850 mV output confirms successful installation.

  $15–$30

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• CLR Calcium Lime Rust Remover

  For Error 90 descale procedure on WGRTLP and WGRTNG condensing tankless units. Use undiluted in a recirculation loop (submersible pump + hoses to service ports) for 45–60 minutes. Flush thoroughly with clean water for 15 minutes after use. Also available at hardware stores in large jugs for cost efficiency.

  $10–$20

  Buy on Amazon →

• Camco 02162 Electric Water Heater Element Kit

  Replacement element with gasket for WECM and WECS electric storage models — use after confirming open (OL) resistance on element test. Includes element, new gasket, and hardware. Drain tank before removal on screw-in element types.

  $20–$40

  Buy on Amazon →

• Digital Multimeter with Millivolt DC Range

  Required for WV8840 thermopile millivoltage testing (blink codes 1 and 2) and element resistance testing on WECM/WECS models. A meter with a millivolt DC range is essential — most standard multimeters include this range.

  $15–$35

  Buy on Amazon →

Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.

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