Vortex Spa Error Codes ER-3 and ER-4

Spa control keypads help us control the functions of our spas and swim spas. We give them little notice as we go about our day to day relaxation...until we receive the dreaded error message. Don't panic. Stay calm and spa on! Most common error messages can be quickly resolved.

Vortex error codes

There are a large number of spa controllers on the market and it's impossible to discuss all of those here, so we will focus specifically on SpaNet SV controllers – common on Vortex spas and swim spas.

Error messages ER-3 and ER-4 on a spa

These errors are most commonly seen at startup or when you empty and refill your spa.

ER-3 is the water prime error

Problem: Water prime failed – air detected in the heater tube.

Cause: Airlock in pipework, low water level, dirty filter cartridges.


  • Press Pump A button to retry water prime
  • Check spa water level (refill if necessary)
  • Remove filter cartridges and press Pump A button to retry prime
  • Remove filter cartridges and flush water down pipe work with a hose
  • Bleed airlock from pipework by slightly loosening couplings on front of filtration.

Important note

The restriction of water flow due to dirty filter cartridges is the most common cause of the ER-3 fault in spas and swims spas. If the spa pool has been operating normally then intermittent ER-3 faults start to occur the filter cartridges will require servicing.

Depending on the type of filter that is installed the cartridges will either require a filter cartridge cleaning and soaking in a filter cartridge cleaning solution or the filter will need replacing altogether.


Do not allow the spa filtration pump to continue to run after five (5) x failed priming attempts.

Operating a spa or swim pump without water for extended periods may cause damage to the pump. Turn power off, wait ten (10) minutes and then try again later. The in-heater water sensor constantly monitors the presence of water in the heater tube.

If at any time air bubbles are detected the spa controller will automatically cancel all current operations and force a water priming sequence to begin. This will occur whether the spa is in automatic mode or manual use. If the priming sequence is successful in clearing the air pockets from the plumbing normal spa operation will resume in automatic mode.

If unsuccessful the spa controller will shut down and latch on fault code ER-3 Water Prime

ER-4 error message

ER-4 error message is the thermal trip.

Problem: Heater thermal trip activated. The heater has been active and has had insufficient water flow over the element. Low or no water flow has caused the heater temperature to exceed its maximum limits and the spa control has shut down operation to prevent any damage to the heater unit.

Cause: Low water level, an airlock in pipework, closed shut-off valves, dirty filter cartridges, filtration pump failed or operation intermittent.


  • Turn mains power OFF and wait 10-15 minutes for the element to cool and thermal cut-out device to reset. Then turn the power back ON
  • Check spa water level (refill if necessary)
  • Remove filters and clean as per manufacturer’s recommendations or replace cartridges if required.
  • Check under spa cabinet to ensure all shut-off valves are in the OPEN position.
  • Bleed airlock from spa pipework by slightly loosening couplings on the front of filtration pump or by removing filters and flushing water down pipe work with a hose.

Download the SpaNet SV controller troubleshooting guide for more error code solutions.

Download the SpaNet SX controller troubleshooting guide for more error code solutions.

Tips on filling your spa to avoid ER-3 and ER-4

Before filling, remove the spa cabinet and be sure that all valves in the plumbing system are fully open to maximise the amount of air that can escape the pipe work during filling.

Remove spa filter cartridges before filling and be sure to fill the spa through the filter itself to flood the pipework with water and minimise the chance of air pockets forming in the plumbing during the filling process.

Do not fill spa by placing the hose in the footwell. Filling a spa this way will create a large number of air pockets in the pipe work and may cause difficulty when priming. Always fill the spa through the filter area.

Once the spa is filled to the correct level attempt to power up the spa with the spa filter cartridges still removed. Verify that the spa controller completes it's priming sequence and begins normal operation. Once the normal operation has been verified turn mains power off, re-install filter cartridge(s) and restart spa.

If you have questions about your spa controller please contact us.

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