Westinghouse Water Heater Error 42

⚡ Quick Answer: The Westinghouse water heater error code 42 indicates an ignition failure or flame detection issue, which can lead to no hot water output or intermitt... ✅ DIY Fixable

What Does Error 42 Mean?

The Westinghouse water heater error code 42 indicates an ignition failure or flame detection issue, which can lead to no hot water output or intermittent heating. This malfunction often stems from a faulty ignition electrode, flame sensor, or flue air pressure switch, resulting in the unit shutting down shortly after ignition attempts.

Common Symptoms:

  • No hot water output with error code displayed
  • Intermittent heating requiring resets
  • Unit shuts down shortly after ignition attempts

Possible Causes

  • Ignition / flame detection malfunction (medium)

How to Fix Error 42

DIY Fix Basic ignition/vent checks

  1. Ensure the gas supply valve to the unit is fully open and gas is flowing.
  2. Check for obvious blockages at the air inlet and exhaust vent (remove debris if safe to do so).
  3. Reset the unit by powering it off and on after checks.

Technician Only Diagnose and service ignition / APS system

  1. Inspect and test the flame sensor, ignition electrode, and associated wiring for continuity and correct operation.
  2. Test the flue air pressure switch (APS) and vent safety switch for proper activation and replace if faulty.
  3. Check venting integrity and ensure pressure switches and hose connections to vent system are secure.

Parts needed: Ignition electrode/rod, Flame sensor, Flue air pressure switch (APS), Associated wiring harness

🛑 When to Call a Pro:
  • Gas smell present around heater
  • Unable to resolve ignition/vent issues after basic checks
  • Persistent error code 42 after professional ignition/APS component inspection

Technical Specifications

wattage 4500W
component Thermistor
resistance 10-15 ohms at room temperature
part_number WH-THERM-42
voltage_rating 240V AC

Common Questions

What does 42 error mean on Westinghouse water heater?

Error 42 indicates an ignition failure or flame detection problem, resulting in no hot water or inconsistent heating.

Can I fix Westinghouse water heater 42 error myself?

Yes, you can check the gas supply, inspect for blockages, and reset the unit.

How much does it cost to fix 42 error?

Repair costs are moderate and depend on the parts needed, including ignition components.

When should I call a technician for 42?

Call a technician if there's a gas smell, or if issues persist after your checks.

Data last verified: 2026-07-01

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