What are ER-3 and ER-4 Error Messages

Spa control keypads are wonderful tools that help us communicate and control most of the functions on our spas and swim spas.

We hardly give them any notice as we go about our day to day relaxation...until we receive a dreaded error message.

"Not to fear, many common error messages can be quickly resolved."

There are a large number of spa controllers on the market and so it is impossible to discuss all of those here so we will focus specifically on SpaNet SV controllers common in Vortex spas, Oasis spas, Escape spas and many more.
Here are all the spa controllers on the market.
The most common error messages are ER-3 and ER-4.

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


Problem: Water prime failed – air detected in heater tube

Cause: Airlock in pipe work, 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 pipe work by slightly loosening couplings on front of filtration.


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 a filter cartridge cleaning solution or the filter will need replacing all together.


Do not allow the spa filtration pump to continue to run after five (5) x failed priming attempts. Operating a spa pump without water for extended periods may cause damage to the pump. Turns 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.


Heater thermal trip activated. 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


Low water level, airlock in pipe work, closed shut-off valves, dirty filter cartridges, filtration pump failed or operation intermittent


Turn mains power OFF and wait 10-15 minutes for element to cool and thermal cut-out device to reset. Then turn 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 pipe work by slightly loosening couplings on front of filtration pump or by removing filters and flushing water down pipe work with a hose.

For complete troubleshooting help click here to download the SpaNet SV controller guide. Do you have questions about your spa? Ask them below.


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