A.O. Smith gas water heater shows E03 and shuts down shortly after ignition attempt
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety: Turn off power to the heater and shut off gas before servicing. Do not operate the unit with venting disconnected.
- 1. Inspect venting: Follow the PVC or metal vent pipe from the heater to the termination. Check for kinks, sags, disconnections, bird nests, leaves, or ice buildup at the termination. Clear any obstructions.
- 2. Check air intake: On direct-vent models, inspect the intake pipe and termination for blockages. Clean screens and ensure adequate clearance from snow, shrubs, or debris.
- 3. Condensate drain: If your model has a condensate trap or drain line, verify it is not clogged or frozen. Clear the trap and ensure the line slopes properly to a drain.
- 4. Pressure switch tubing: Remove the small rubber or silicone tube from the pressure switch and check for water, debris, or cracks. Blow through the tube to clear it and reattach securely.
- 5. Test pressure switch: With power off, inspect the wiring connections to the pressure switch. Tighten loose spade terminals. A technician can test continuity across the switch while the blower runs; if it does not close, the switch may be defective.
If E03 remains after clearing vents and tubing, have a professional test and replace the pressure switch or blower assembly as needed.
Repair Difficulty
Required Part
We may earn a commission from links on this page.