Equipment error code

AO Smith code E02

E02 — dry fire or insufficient water in tank. The upper element or heat pump loop detected operation without adequate water surrounding the heater.

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

What this code means

E02 — dry fire or insufficient water in tank. The upper element or heat pump loop detected operation without adequate water surrounding the heater.

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

Which models show it

AO Smith Voltex and ProLine heat pump water heaters with digital diagnostics.

What is actually happening

Unit shuts down; display shows E02. Often follows closed valves, failed fill, or leak draining tank.

Is it safe to keep running?

Do not reset repeatedly — dry firing electric elements destroys them in seconds.

Shut it down when

Active leak, hissing at T&P valve, or tank feels unusually hot on exterior.

What a homeowner can safely check

Confirm cold water supply valve to heater is fully open.
Open a hot tap upstairs to verify water flows — not just sputter.
Check pan for water — leak may have tripped dry fire logic.
Power off at breaker until water level confirmed if you suspect empty tank.

When to stop

Cannot get steady water at hot tap.
Visible tank leak.
E02 returns after refill.

Likely causes ranked

1. Closed or partially closed cold inlet valve
How a tech confirms: Verifies flow; opens valves and purges air.
Typical repair: $125–$275 · Water Heater Replacement cost guide
2. Failed dip tube or cross connection
How a tech confirms: Flow tests hot and cold lines; inspects dip tube.
Typical repair: $200–$550 · Water Heater Replacement cost guide
3. Tank leak lowering water below element
How a tech confirms: Visual and pressure test; replaces heater if tank leaking.
Typical repair: $1,200–$2,800 · Water Heater Replacement cost guide
4. Faulty water level or dry-fire sensor
How a tech confirms: Tests sensor per AO Smith service bulletin.
Typical repair: $250–$500 · Water Heater Replacement cost guide

Is this the end of this unit?

Tank leak with E02 means replace the water heater — element replacement alone will not fix a failed tank.

How to clear the code

Restore water flow, purge air from hot lines, power cycle once at breaker after tank is full.

Why clearing is not fixing it: E02 protects against dry fire — returns if water level or flow is still inadequate.

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 E02 meaning?

Dry fire protection — heater sensed insufficient water for safe heating.

E02 after plumbing work?

Common if valves left closed — open supply and purge air.

Can E02 burn out elements?

Yes if ignored — keep breaker off until tank is full.

E02 repair cost?

$125–$550 for valve or dip tube; $1,200+ if tank leaked.

E02 on Voltex heat pump?

Same dry-fire logic applies to heat pump and backup element modes.

Source

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