AO Smith Water Heater Error Code 031: Water Leak Detected (Meaning, Causes, Fixes)

What the code means

In A. O. Smith's Residential Electronic Thermostat Electric Water Heater Use and Care Guide (the Wi-Fi, Energy Smart display model sold at Lowe's), diagnostic code 031 with a flashing alert icon, flashing red LED and beeper is listed as Water Leak. The same code and the same corrective steps appear in A. O. Smith's Residential Hybrid Electric Heat Pump Water Heater Service Handbook (HPTS, HPTA and HPTV models and their HPS10, HPA10 and HPV10 retail versions). The code comes from the leak detect sensor (LDS), a small sensor plugged into the control and taped to the heater or drain pan with its metal probes pointing down. A. O. Smith is clear that the sensor doesn't protect against a leak; it only tells you that water is present where the sensor sits. So 031 means water reached the sensor, which could be a tank leak, a dripping pipe connection, relief-valve discharge or any other water on the floor or in the pan. Don't confuse it with 046, which is a shut-off valve error on models that have the automatic cold water shut-off valve, or, on the hybrid models, with 081, which means the condensate drain pan overflow switch tripped.

Likely causes

• A leak at a pipe connection, union or fitting near the heater. A. O. Smith's guide says almost all leaks occur at connections and are not a tank leak
• Water discharged from the temperature and pressure (T&P) relief valve or its drain line, or from a dripping drain valve
• A leaking tank. A. O. Smith says that if the tank itself is leaking, the unit has to be replaced
• Water on the floor or in the drain pan from something else, such as a nearby appliance, a spill or condensation, reaching the sensor's probes
• Damaged sensor wiring or a loose connection. A. O. Smith's first step for 031 is to check all electrical connections and wiring for damage

Safe DIY checks

1. Turn off the water heater's breaker. A. O. Smith's guide says that when the sensor shows water, you should disconnect power, turn off the incoming cold water, and deal with the source of the leak before putting the heater back in service.
2. Look and feel around the heater: the cold and hot pipe connections on top, the T&P relief valve and its discharge pipe, the drain valve near the bottom, and the drain pan. Dry everything with a towel so a fresh drip will be easy to see.
3. Find where the sensor is. It's normally taped to the heater or drain pan with its metal probes pointing down, and plugged into the lower connector on the control. Dry the sensor and the area under it.
4. With the power still off, check the sensor's wire and plug, and the other wiring you can see, for damage, as A. O. Smith's 031 steps say.
5. Fix any plumbing leak you find (for example, tighten or reseal a leaking fitting). If water is coming from the tank itself, A. O. Smith says the water heater must be replaced; leave the water and power off.
6. Once the area is dry and the leak is fixed, turn the cold water back on, check for drips again, and turn the breaker back on. 031 should not come back.

Parts that commonly fix it

Always match the part number to your exact model.

Related codes

• 002 AO Smith Electric Water Heater 002
• 084 AO Smith Heat Pump Water Heater 084
• E09 Bosch Dishwasher E09
• E15 Bosch Dishwasher E15
• E22 Bosch Dishwasher E22

All AO Smith codes →

Sources

1. A. O. Smith Residential Electronic Thermostat Electric Water Heater Installation Instructions and Use & Care Guide (aosmithatlowes.com): diagnostic code 031 (Water Leak) and its corrective actions, 046 shut-off valve error, Installing the Leak Detection Sensor (Step 10), drain pan and leak notes
2. A. O. Smith Residential Hybrid Electric Heat Pump Water Heater Service Handbook (assets.hotwater.com): diagnostic code 031 (Water Leak), 046 shut-off valve, 081 condensate drain pan overflow switch, leak detection sensor location