HPt, Hd, and Prr are probe or heater-safety messages. They are not filter-maintenance codes, and Spa Filter Adapter Kit v3 does not repair them.
| Code | Official meaning | Owner-safe response |
|---|---|---|
| HPt / ER 10 | Heater probe test failed | Stop normal use; service the probe attachment/system if it returns |
| Hd / ER 09 | Heater high-limit probe disconnected from the board | Power off and have the connection inspected |
| Prr / ER 04 | Spa temperature probe disconnected/problem | Do not rely on heater control; arrange service |
HPt: heater probe test failed
At startup the control system checks that the high-limit probe is attached to the heater barrel. The display can show tSt during the test. HPt appears when that test fails. Arctic Spas’ detailed code page directs service to locate the high-limit probe and restore correct attachment to the heater barrel.
Hd: high-limit probe disconnected
Hd appears when the high-limit probe is disconnected from the board. Arctic Spas’ service guidance calls for checking the board connection, cleaning the terminals when appropriate, and reconnecting it. That work is inside the equipment/control area and is not an energized owner task.
Prr: spa temperature probe problem
Prr appears when the main temperature probe is disconnected from the base board. Without that feedback, the spa pack cannot safely control heater operation, so the heater is prevented from running.
What an owner can check
- Record the exact code and whether it appeared during startup.
- Turn power off at the breaker.
- Do not open or work inside the control pack unless qualified.
- Cycle power once after a normal shutdown.
- If the code returns, provide the code, model, year, and serial information to an Arctic Spas dealer or qualified spa technician.
Why filters do not fix these codes
A restricted filter can contribute to FLO or heater high-limit conditions, but it cannot reconnect a probe or restore a failed probe test. Buying filters or Kit v3 as a response to HPt, Hd, or Prr is the wrong repair path.
Startup sequence and code timing
On power-up the controller performs the heater-probe attachment test and can display tSt while that check runs. HPt during this sequence identifies a failed test. Hd identifies the board-side high-limit probe connection, while Prr identifies the main spa-temperature probe circuit. Note whether the code appears immediately at startup or after heating begins; the timing helps service personnel isolate the correct circuit.
What to document before service
- The exact capitalization shown on the topside: HPt, Hd, or Prr.
- Any ER number shown in the app or web dashboard.
- The model, year, serial information, and controller generation.
- Whether the code appeared after a refill, freeze event, equipment service, or power interruption.
- Any accompanying HL, FLO, FLC, breaker, pump, or heating symptom.
Do not remove panels solely to gather this information. The topside, app, serial plate, and service history provide the safe owner-level record.
Do not bypass the safety system
Do not jumper probe connections, defeat the heater interlock, repeatedly reset the breaker, or continue using the spa when temperature feedback is unavailable. These protections exist to prevent unsafe water temperature and heater damage.
Do not replace parts from the code name alone
HPt, Hd, and Prr narrow the fault to specific probe functions, but the technician still needs to inspect attachment, connectors, wiring, sensor condition, and the controller input. Ordering a probe before that inspection can replace a good component while leaving a loose connector or damaged harness unresolved.
FAQs
What does HPt mean on an Arctic Spa?
The heater probe attachment test failed. If it returns after one restart, the heater-barrel probe system requires service.
What does Hd mean?
The heater high-limit probe is disconnected from the control board.
What does Prr mean?
The spa temperature probe is disconnected or its circuit is not providing valid temperature feedback.
Can Kit v3 clear HPt, Hd, or Prr?
No. Kit v3 changes the filter interface only. It does not alter probes, heaters, control boards, or wiring.
References
This is an independent aftermarket owner resource. Spa Filter Adapter is not affiliated with, endorsed by, or approved by Arctic Spas. Product and maintenance claims are separated by system and tied to the sources below.