Rinnai Error Code 21: PC board data transfer error (Tankless)
Rinnai error code 21 on a tankless water heater means: PC board data transfer error. It is also called Rinnai diagnostic code 21.
Homeowner? What Rinnai code 21 means for you
Call a technician Your tankless water heater is reporting: PC board data transfer error. The tankless water heater has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Safe things you can check yourself
- Check that gas reaches the house: other gas appliances work, or the propane tank is not empty.
- Make sure the heater is plugged in and its breaker is on. In winter, keep the power on: it protects the unit from freezing.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the hot and cold water valves under the heater are fully open.
- If you have a remote controller, turn it off and on once. If the code comes back, call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Rinnai error code 21 mean?
Data/parameter transfer to a PC board (typically a replacement board) did not complete correctly.
Applies to: SENSEI Series; SENSEI RX/CX Series
Common causes of Rinnai code 21
- Data transfer incomplete after PC board replacement
- Parameters not programmed correctly for the model
- Board replacement/data transfer instructions not followed
A technician checks these and 1 other possible causes on site before replacing any part.
Rinnai models that use code 21
Show all 30 models
CU160eCU160iCU199eCU199iCX160iCX199iCXP160iCXP199iRSC160eRSC160iRSC199eRSC199iRU130eRU130iRU160eRU160iRU180eRU180iRU199eRU199iRUR160eRUR160iRUR199eRUR199iRX130iRX160iRX180iRX199iRXP160iRXP199i
Other Rinnai Tankless codes
All Rinnai Tankless Water Heater error codes →
Rinnai code 21: homeowner questions
What does Rinnai code 21 mean?
PC board data transfer error. Data/parameter transfer to a PC board (typically a replacement board) did not complete correctly.
Is it safe to keep using my tankless water heater with code 21?
It depends on the cause. The tankless water heater has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Can I reset Rinnai code 21 myself?
You can try one reset (power off for 30 seconds, then on). If Rinnai code 21 comes back, the cause is still there and a licensed technician should check it.
Who can fix Rinnai code 21 near me?
Aurora Star Tech Inc. repairs Rinnai tankless water heaters in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Tankless Water Heater No Hot Water: What to Check
Troubleshooting guides
- No hot water All brands · Tankless Water Heater
- Water temperature fluctuates All brands · Tankless Water Heater
Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.32. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.