Product Description
Balboa Temperature & Hi-Limit Sensor Set – 4 Pin
Dual 1/4" Probe Sensors – 96" Cables
This Balboa Temperature & Hi-Limit Combination Sensor Set uses two 1/4" diameter probes, which is different from most standard Balboa sensor sets where the temperature probe is typically larger.
This smaller probe configuration is commonly found on spas that do not use a traditional heater tube. Instead, these systems use:
• Firestick heaters
• Heat jackets
• Other in-line heating methods built into the plumbing
Because of this design, the temperature sensor installs into a thermowell located in the plumbing line, not in the spa shell wall like many other systems.
This sensor style has been seen on Dreammaker Spas and several other brands that use similar heating systems.
Sensor Specifications
Temperature Sensor Probe Diameter: 1/4"
High Limit Sensor Probe Diameter: 1/4"
Temperature Sensor Cable Length: 96 inches
High Limit Sensor Cable Length: 96 inches
Connector Type: 4-Pin Curly Finger Style
Wire Count: 2 Wire / 2 Wire
Sensor Type: Temperature & High Limit Combination
Application: Spa Control Systems
Manufacturer Application: Balboa Water Group
System Type: Balboa 4-Pin Sensor System (Non-M7)
Important Measurement Information
Most Balboa sensor sets use a larger temperature probe and a smaller high-limit probe.
This sensor set is different, because both probes are 1/4" diameter.
Before ordering, always:
• Measure both probes on your existing sensor
• Confirm both probes are 1/4" diameter
Ordering the wrong probe size will prevent proper installation.
Typical Sensor Locations
On spas that use this sensor set:
The temperature sensor is usually installed in a thermowell located in the plumbing line.
The high-limit sensor may be mounted in the heater assembly, plumbing line, or heating device depending on the spa design.
These systems typically do not use a traditional heater tube.
Diagnostic Information – SN Error Code
An SN error code indicates the spa control system cannot properly read one of the sensors.
Before replacing the sensor set, check these common issues.
Step 1 – Check the Board Connection
Turn power OFF to the spa.
Unplug the 4-pin sensor connector from the control board.
Inspect for:
• Loose connection
• Corrosion
• Dirty contacts
Clean the connector and plug it back in firmly.
Restore power and see if the error clears.
Many SN errors are caused by poor connections rather than a failed sensor.
Step 2 – Inspect the Wiring
Check the sensor wires for:
• Cuts
• Rodent damage
• Pinched wiring
• Broken insulation
Damage to the wiring harness can trigger an SN sensor error.
Step 3 – Replace the Sensor Assembly
If wiring and connections are good and the SN error remains, the sensor assembly may need to be replaced.
Sensor failures are possible but not extremely common, so always diagnose before replacing parts.
Replacement For Part Numbers
This sensor kit replaces the following part numbers:
30278
59-138-1068
030278
9711-310
BAL30278
BAL30278KIT
BWG30278
BWG30278KIT
BB30278
BB30278KIT
Dream Maker Spas 400782
Return Policy Notice
Electrical components cannot be returned once installed.
Always verify the probe diameter and cable length before ordering.
Know Before You Go.
| Sensor Application | Spa Control |
| Sensor Type | Temp and Hi Limit |
| Application | Balboa Water Group |
| Model | Balboa 4 Pin |
| Connector Type | 4 pin |
| Sensor Diameter | 1/4" & 1/4" |
| Wire Count | 4 wire |
| Wire Length | 96" & 31" |
Spa Sensor Diagnostic Guide (Read Before Ordering)
Many spa error codes are related to sensors, but sensors are not always the actual cause of the problem. Before replacing a sensor, take a few minutes to diagnose the spa properly.
Common Spa Sensor Error Codes
- SN / Sn1 / Sn2 – Sensor communication error
- OH / OHH – Overheat condition
- HL – High limit trip
Step 1 – Check the Board Connection
Turn power OFF to the spa before inspecting any components.
- Unplug the sensor connector from the control board
- Inspect the connector pins
- Look for corrosion or debris
- Plug the connector back in firmly
Many sensor errors are simply caused by a loose or dirty board connection.
Step 2 – Inspect the Sensor Wiring
Sensor wiring runs through the cabinet where rodents and insects sometimes damage wires.
Look for:
- Chewed wires
- Pinched wiring
- Broken insulation
- Loose connections
Even a small break in the wire can cause the control system to report a sensor error.
Step 3 – Verify the Correct Sensor Type
There are several different sensor systems used in spas.
- Balboa 4-Pin Sensor Set (Temp & Hi Limit combined harness)
- M7 Sensors (two sensors mounted in the heater tube)
- Single Temperature Sensors
- Thermowell Style Sensors
Always verify:
- Probe diameter
- Wire length
- Connector type
- Sensor location
Ordering the wrong sensor type will prevent proper installation.
Step 4 – Understand Other Causes of Error Codes
Some spa error codes are not caused by sensors at all.
Overheat (OH) errors can also be caused by:
- Dirty or clogged filters
- Low water flow
- Failed circulation pump
- Pressure switch stuck closed
- Heater relay stuck closed on the control board
- Restricted plumbing
Always diagnose the spa system before replacing parts.
Important Electrical Parts Policy
Electrical components cannot be returned once installed.
Please verify the correct part number and diagnose the spa properly before ordering.
Know Before You Go.
