Rheem HVAC Error Code 27: How to Fix It
Medium 30-60 minutes Medium Severity
Verified June 2026
- Error Code
- 27
- Brand
- Rheem
- Product Type
- hvac
- Severity
- Medium
- DIY Difficulty
- Medium
- Estimated Fix Time
- 30-60 minutes
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Tools You'll Need
- Multimeter
- Screwdriver (to access control board)
- Wire strippers or cutters (if replacing sensor)
How to Fix Error Code 27
-
Turn Off Power to the Unit
Always disconnect power before servicing the unit. -
Locate the Liquid Line Sensor
-
Inspect Sensor Connection
-
Test the Sensor with a Multimeter
Be careful not to damage the sensor wires. -
Replace the Faulty Sensor
Ensure the new sensor is properly positioned and secured for accurate readings. -
Restore Power and Test
Parts You May Need
Liquid line sensor (thermistor)
Check Price on Amazon
Liquid line sensor (thermistor)
Check Price on Amazon
Liquid line sensor (thermistor)
Check Price on Amazon
Liquid line sensor (thermistor)
Check Price on Amazon
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When to Call a Professional
Call a professional HVAC technician if you are uncomfortable working with electrical components, if the error persists after sensor replacement, or if you suspect a deeper issue like a defective control board.Frequently Asked Questions
What does Rheem error code 27 mean?
Rheem error code 27 means a liquid line sensor fault – the sensor monitoring the refrigerant line temperature is malfunctioning.
Can I drive my Rheem HVAC with error code 27?
It's not recommended. The system may shut down or operate inefficiently, potentially causing damage. It's best to fix the sensor issue promptly.
Is a liquid line sensor the same as a thermistor?
Yes, the liquid line sensor is a type of thermistor that measures temperature by changing resistance.
Where can I buy a replacement liquid line sensor for my Rheem unit?
You can purchase a compatible sensor from HVAC supply stores, online retailers like Amazon, or directly from Rheem dealers.
How do I know if the sensor is bad?
Use a multimeter to check resistance. If it reads infinite (open) or 0 (short), or if the resistance is far from the expected value at a known temperature, the sensor is likely bad.