A.O. Smith Error Code E06: Flammable Vapor Detection

Severity
Critical
Type
digital display
Estimated repair cost: $100 — $350 (parts + labor)
Warning: The water heater has detected flammable vapors, indicating a potential fire or explosion hazard. Shut down the unit immediately and evacuate the area.

How to Fix A.O. Smith Code E06

  1. Step 1: Immediately shut off the gas supply to the water heater at the manual shut-off valve.
  2. Step 2: Evacuate the area and ensure everyone is a safe distance away from the water heater.
  3. Step 3: Do not attempt to operate any electrical switches or devices, as this could create a spark.
  4. Step 4: Contact your local fire department or a qualified HVAC technician or gas company from a safe location to investigate the source of the flammable vapors.

How to Reset A.O. Smith Code E06

  1. Turn off the unit using the power button on the front panel.
  2. Turn off the gas supply valve.
  3. Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
  4. Restore power at the breaker, then open the gas valve.
  5. Turn the unit back on. If the error returns, the underlying issue needs repair.

Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.

What Does A.O. Smith Error Code E06 Mean?

The E06 error code on your A.O. Smith water heater indicates that the unit's flammable vapor sensor has detected the presence of potentially explosive gases. This is a serious safety concern. The water heater is designed to shut down automatically to prevent ignition of these vapors. This sensor is located near the base of the unit to detect heavier-than-air gases like propane or natural gas. It's important to address this issue immediately to prevent a fire or explosion. The unit will remain locked out until the issue is resolved and the system is reset.

Common Causes

  • Gas leak near the water heater (natural gas or propane)
  • Spilled flammable liquids (gasoline, solvents, etc.) in the vicinity of the water heater
  • Malfunctioning flammable vapor sensor
  • Improper venting of nearby appliances causing gas buildup

Diagnostic Steps

If... Check Expected
Gas odor is present Use a combustible gas leak detector to pinpoint the source of the leak around the water heater and gas line connections. No gas leak detected.
No gas leak is detected Inspect the flammable vapor sensor for damage or contamination. Sensor is clean and undamaged.
Sensor appears normal Using a multimeter, check the sensor's resistance. Refer to the A.O. Smith technical manual for the correct resistance range for the specific model. Resistance within specified range.
Resistance is out of range Check wiring harness continuity from sensor to the control board. Good continuity on all wires.

Applicable A.O. Smith Models

Replacement Parts

Part OEM Number Est. Cost Where to Buy
Flammable Vapor Sensor 9007618005 — Find Part
Gas Control Valve — — —
Electronic Control Board — — —

Related Codes on Same Models

Other codes that affect the same A.O. Smith model families as E06.

Code Description Severity
E1 Thermistor Failure Warning
E2 Dry Fire Protection Warning
E3 Sensor Fault Warning
E4 High Temperature Cutoff Critical
E5 Communication Error Warning
ECO Emergency Cutoff Critical
LOC Controls Locked Warning
LWR Lower Element Fault Warning
UPR Upper Element Fault Warning