Equipment error code

AO Smith code E03

E03 — upper heating element fault. The control detected an open circuit, short, or abnormal resistance on the upper element.

Equipment: water heater
Brand: AO Smith
Source checked: 2026-03-01

What this code means

E03 — upper heating element fault. The control detected an open circuit, short, or abnormal resistance on the upper element.

Source: AO Smith Voltex Heat Pump Water Heater Owner's Manual — Diagnostic Codes · checked 2026-03-01

Which models show it

AO Smith Voltex, ProLine, and standard electric residential tanks with electronic diagnostics.

What is actually happening

Lukewarm water at taps; short hot bursts possible. Display shows E03.

Is it safe to keep running?

Lower element may still heat some water — adequate for short term but not normal operation.

Shut it down when

Breaker trips, burning smell at heater, or water leaking from connections.

What a homeowner can safely check

Reset dedicated water heater breaker once.
Confirm no recent flooding around unit.
Check that upper thermostat cover panel is properly seated.

When to stop

Breaker trips again.
Scorched wiring visible after removing cover — do not touch energized parts.

Likely causes ranked

1. Failed upper heating element
How a tech confirms: Ohms element; replaces if open.
Typical repair: $225–$450 · Water Heater Replacement cost guide
2. Upper thermostat or wiring failure
How a tech confirms: Tests thermostat contacts and wire nuts.
Typical repair: $175–$385 · Water Heater Replacement cost guide
3. Dry-fired damaged element from prior E02 event
How a tech confirms: Visual element inspection; replace both elements if swollen.
Typical repair: $250–$525 · Water Heater Replacement cost guide
4. Control board output failure
How a tech confirms: Voltage to element during call; board replacement.
Typical repair: $350–$650 · Water Heater Replacement cost guide

Is this the end of this unit?

Element plus board on tanks over 10 years — compare to new heat pump or electric tank efficiency.

How to clear the code

Breaker reset once after cooling; if E03 returns within an hour, schedule service.

Why clearing is not fixing it: Open element circuit persists until element or wiring is replaced.

Which trade to call

Call a licensed plumber who works on water heater equipment. Gas, refrigerant, and combustion faults are not general handyman jobs.

How to find a good plumber

Before you sign a contract for this job, use our guide on how to find a good plumber: verify the licence at the state board, compare three itemized quotes on the same scope, and put permit responsibility and change-order rules in writing.

Read the plumber hire guide Check if your quote is fair Verify licences by state

More codes from this brand

Symptom guide: No Hot Water

FAQ

AO Smith E03?

Upper element electrical fault.

Still some hot water with E03?

Lower element may work — upper handles quick draws and recovery.

E03 DIY element change?

Requires draining and electrical isolation — many homeowners hire plumbers.

Cost to fix E03?

$175–$650 depending on element, thermostat, or board.

E03 after E02?

Dry fire may have destroyed upper element — replace element after fixing water supply.

Source

Source — AO Smith Voltex Heat Pump Water Heater Owner's Manual — Diagnostic Codes. Checked 2026-03-01.