A.O. Smith Error Code LWR: Lower Element Fault
How to Fix A.O. Smith Code LWR
- Step 1: Check the water heater's circuit breaker in your electrical panel. Ensure it hasn't tripped. If it has, reset it. If it trips again immediately, do not reset it again and call a qualified technician.
- Step 2: If the breaker is fine, check the reset button on the water heater (usually a red button near the top). Press it firmly. If it clicks, that indicates the high limit switch had tripped. This might restore operation, but it's still important to have a technician investigate the underlying cause.
- Step 3: If the problem persists after checking the breaker and reset button, contact a qualified HVAC technician or electrician to diagnose and repair the issue.
How to Reset A.O. Smith Code LWR
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- 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 LWR Mean?
The 'LWR' error code on your A.O. Smith water heater indicates a problem with the lower heating element circuit. The control board monitors the electrical current flowing through the heating elements. If it detects a short circuit, open circuit, or other electrical anomaly, it will display this error and shut down the element to prevent further damage or potential fire hazard. This usually means the element has failed, or there's a wiring issue. Because the water heater relies on both elements to properly heat water, a fault in one will prevent the unit from operating correctly. The lower element is especially important as it heats the larger volume of water at the bottom of the tank.
Common Causes
- Failed lower heating element (most common)
- Loose or corroded wiring connections at the lower heating element
- Sediment buildup on the lower heating element causing it to overheat and fail
- Faulty thermostat or high limit switch preventing proper element operation
- Defective control board not properly reading the current draw of the lower element
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Water heater displays 'LWR' error | Measure voltage at the lower heating element terminals with the breaker on and the thermostat calling for heat. | 240 VAC (or 120 VAC depending on the model) |
| No voltage at the element terminals | Check continuity of the high limit switch. | Continuity (closed circuit) |
| Voltage is present at the element | Disconnect power and measure resistance across the lower heating element terminals. | Around 10-15 ohms (will vary slightly depending on element wattage). An open circuit (OL) indicates a failed element. |
| Element resistance is within range | Inspect wiring connections at the element and control board for corrosion or looseness. | Clean, tight connections |
Applicable A.O. Smith Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Lower Heating Element | 9000766 | — | Find Part |
| High Limit Switch | 100112098 | — | Find Part |
| Thermistor | — | — | — |
Related Codes on Same Models
Other codes that affect the same A.O. Smith model families as LWR.
| Code | Description | Severity |
|---|---|---|
| E06 | Flammable Vapor Detection | Critical |
| 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 |
| UPR | Upper Element Fault | Warning |