Hitachi Water Heater Error 3

⚡ Quick Answer: The Hitachi water heater error code 3 (Er03) indicates an abnormality in the 150L tank temperature sensor, which can lead to issues such as improper w... ⚠️ Difficulty Varies

What Does Error 3 Mean?

The Hitachi water heater error code 3 (Er03) indicates an abnormality in the 150L tank temperature sensor, which can lead to issues such as improper water temperature regulation and unusual clicking noises. The system may stop heating entirely if the sensor readings are faulty, requiring attention to ensure consistent hot water supply.

Common Symptoms:

  • Error code Er03 displayed on the unit/control
  • Possible incorrect water temperature or inability to properly regulate tank temperature
  • System may shut down or stop heating due to abnormal sensor reading

Possible Causes

  • Temperature sensor (150 L section) fault (medium)
  • Temperature sensor wiring issue (open circuit, short, connector problem) (medium)
  • Control board misinterpreting temperature sensor signal (low)

How to Fix Error 3

DIY Fix Power cycle and basic check

  1. Turn off the main breaker or power switch to the water heater.
  2. Wait at least 10 seconds and then restore power.
  3. Check whether the error code clears upon restart.

Technician Only Inspect and test temperature sensor and wiring

  1. Disconnect power to the unit.
  2. Access the 150 L tank temperature sensor location per service manual.
  3. Measure resistance of the temperature sensor and compare with manufacturer specs.
  4. Inspect wiring harness and connectors to the sensor for continuity and secure contact.
  5. Replace the temperature sensor or repair wiring as needed.

Parts needed: 150 L tank temperature sensor, Wiring harness/connectors

🛑 When to Call a Pro:
  • Error persists after power cycling
  • Sensor tests show out‑of‑range resistance or open circuit
  • Wiring appears damaged and beyond simple reconnection

Next step

Choose the next step for 3

Confirm the diagnosis before ordering. An error code can identify the system involved, but it does not prove that a specific part has failed.

Check during diagnosis

Most relevant component to inspect

Temperature Sensor

Monitors the internal temperature to ensure correct operation and prevent overheating.

Typical part-only price
$15 - $35
DIY difficulty
Easy
Estimated time
15-30 mins
Where can I find the model number?

Check the rating label around the door, lid, frame, rear panel, or inside the appliance cabinet. Use the complete model number, including suffixes.

Find a part that fits my model

Verify the complete model and part number on the retailer's compatibility page before ordering.

Other parts options

Check related components first; use model search as a fallback.

Possible related component

Wiring Harness

Connects controls, sensors, motors, and other electrical components inside the appliance.

$20 - $120 · Medium · 30-90 mins

Check fit & price
Model number required

Model-compatible Water Heater parts

Enter the complete model number to browse compatible replacement parts. This is a model-based parts search, not a diagnosis that a specific component failed.

Find a part that fits my model

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Technical Specifications

note The previous model-independent part specification was removed. Verify the full model number and diagnosis in the manufacturer's official parts catalog before ordering.
part_number None

Common Questions

What does 3 error mean on hitachi water heater?

Error 3 indicates a malfunction in the temperature sensor for the 150L tank, causing heating issues.

Can I fix hitachi water heater 3 error myself?

You can try power cycling the unit. If the error persists, further inspection is needed.

How much does it cost to fix 3 error?

Repair costs for the 3 error range from ¥5,000 to ¥20,000, depending on parts and labor.

When should I call a technician for 3?

Call a technician if the error remains after power cycling or if sensor tests show faulty readings.

Data last verified: 2026-07-31

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