Rinnai Error Code 43: Water Level Circuit Error
Warning: Your Rinnai water heater has detected a water level issue. It's safe to use other appliances, but call a professional for repair.
How to Fix Rinnai Code 43
- Check the water supply to ensure it's turned on and there are no kinks in the hose
- Listen for any unusual noises coming from the water heater, which could indicate a leak
- If you suspect a leak, turn off the water supply and call a professional immediately
How to Reset Rinnai Code 43
- 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 Rinnai Error Code 43 Mean?
Error code 43 on your Rinnai water heater indicates a problem with the water level circuit. This circuit ensures your water heater has enough water to operate safely and efficiently. The most common causes for this error are a faulty water level switch or a low water level in the tank.
Common Causes
- Faulty water level switch
- Low water level in the tank
- Air in the lines causing a false low water level reading
- Faulty temperature and pressure relief valve (T&P valve) causing water to leak
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Water heater is not producing hot water | Water level in the tank | Tank should be full |
| Water heater is producing hot water but not at the set temperature | Temperature and pressure relief valve (T&P valve) | Valve should be functioning properly and not leaking |
Applicable Rinnai Models
- CU(gas)
- HE(dual_fuel)
- HE++ Series(gas)
- I-SERIES(gas)
- NCB(gas)
- NPE(gas)
- RE(gas)
- REP(gas)
- RL(gas)
- RU(gas)
- RUCS(gas)
- RX(gas)
- RXP(gas)
- Rinnai NCB Series(gas)
- Rinnai NPE Series(gas)
- Rinnai R Series(gas)
- Rinnai RL Series(natural_gas)
- Rinnai RU Series(natural_gas)
- Rinnai RUR Series(gas)
- Rinnai VSP(gas)
- V(gas)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Water Level Switch | RIN-1120000000 | — | Find Part |
| Temperature and Pressure Relief Valve (T&P Valve) | RIN-1120000001 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Rinnai model families as 43.
| Code | Description | Severity |
|---|---|---|
| 02 | Stagnant Water Detection | Warning |
| 10 | Air Supply/Exhaust Blockage | Warning |
| 11 | No Ignition | Warning |
| 12 | Flame Failure | Warning |
| 14 | Thermal Fuse | Warning |
| 16 | Over-Temperature | Warning |
| 19 | Electrical Grounding | Warning |
| 25 | Condensate Overflow | Warning |
| 29 | Condensate Neutralizer | Warning |
| 31 | Inlet Thermistor Failure | Warning |