Bradford White RE340S6 40 Gallon 4500W Short Electric Water Heater with Glass Lining MECH-THERMOSTAT Error Fix: Thermostat Failure — Wrong Temperature

Error code MECH-THERMOSTAT on the Bradford White RE340S6 40 Gallon 4500W Short Electric Water Heater with Glass Lining means: Thermostat Failure — Wrong Temperature. The upper or lower thermostat is not controlling the heating element properly, causing water that is too hot, not hot enough, or no hot water at all. Bradford White electric water heaters use two mechanical bimetal thermostats — one upper (with ECO) and one lower. To test: with power ON, use a multimeter to check for 240V across the element terminals when the thermostat should be calling for heat (water is cool). If no voltage reaches the element but the thermostat is calling for heat, the thermostat contacts have failed. Replace with the correct Bradford White replacement thermostat. When replacing, set the temperature to 120°F (factory recommended setting).

The most successful fix is "Test and Replace Faulty Thermostat" (medium difficulty, ~45 minutes). Estimated DIY cost: $15-$25. HomeMD has 2 community-ranked fixes for this error.

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Yes — the top-ranked community fix ("Test and Replace Faulty Thermostat") is rated medium difficulty and takes about 45 minutes. Tools needed: Flathead screwdriver, Phillips screwdriver, Multimeter, Non-contact voltage tester.

DIY cost: $15-$25. Professional repair typically costs $150-$220. Many homeowners save money by trying the top-ranked community fix first.

The Bradford White RE340S6 40 Gallon 4500W Short Electric Water Heater with Glass Lining has 8 other known error codes, including: MECH-ANODE (Anode Rod Depleted — Rotten Egg Smell or Corrosion), MECH-ECO-TRIP (ECO (Energy Cut Off) Tripped — Red Reset Button), MECH-ELEMENT-LOWER (Lower Heating Element Failed), MECH-ELEMENT-UPPER (Upper Heating Element Failed), MECH-INSUFFICIENT-HOT (Not Enough Hot Water — Runs Out Quickly), and 3 more.

Error code MECH-THERMOSTAT also appears on 1 other Bradford White model: RE350T6 50 Gallon 4500W 6-Year Warranty Upright Electric Water Heater. The fix may vary by model, so check each model's specific page for tailored repair steps.