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ErrBase

Carrier Furnace Code 31: Gas Valve Failure

Quick Answer

Carrier furnace Code 31 (3 short, 1 long LED blink) is a gas valve fault. The control board sends 24VAC to the valve solenoid but the valve does not open or opens incorrectly.

Carrier furnace Code 31 (3 short, 1 long LED blink) is a gas valve fault. The control board sends 24VAC to the valve solenoid but the valve does not open or opens incorrectly. Diagnosis requires confirming: gas supply is on and at correct pressure (3.5 inches WC natural gas), the control board is sending 24VAC signal at the valve terminals during heat call, and each valve solenoid coil tests within 20-60 ohms resistance. If voltage is present and coils are in spec but the valve does not open, the valve is mechanically failed and must be replaced by a licensed technician. Do not attempt to repair gas valves internally.

CarrierFurnaceSeverity: highDifficulty: advanced70% DIY Success
Time to Fix
60–180 min
Difficulty
advanced
Parts Cost
$85 – $175
Tools Needed
Multimeter (VAC and resistance settings), Manometer (for gas pressure testing, technician tool)
Wrong code?

Not seeing 31 on your display?

Select what your appliance is actually doing and we'll take you to the right guide.

all carrier furnace LED codes
HUB
flame not detected after ignition
34
fault code reset procedure
RESET

What Does the 31 Code Mean?

The gas valve is not opening when commanded. Could be valve failure, no control board output, insufficient gas supply, or wiring fault.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Gas valve solenoid coil burned out or failed mechanically40%
Gas supply pressure too low or gas shutoff valve partially closed24%
Control board not outputting 24VAC signal to valve14%
Debris or corrosion inside valve seat blocking gas flow12%
Wiring harness to gas valve corroded or disconnected10%

Symptoms You May Notice

  • Inducer and ignitor cycle but no gas ignites
  • Furnace completes all startup steps except gas valve opening
  • Control board LED shows 3 short + 1 long blinks
  • No clicking sound from gas valve area during heating sequence
  • Furnace restarts repeatedly, reaches ignitor glow stage, then shuts down

Can you reset a Carrier furnace to clear the 31 code?

After gas valve replacement or correcting gas supply, reset the furnace by turning the thermostat to OFF for 30 seconds, then back to HEAT. The fault code will clear after one successful heating cycle. If Code 31 persists after verified repair, cycle the circuit breaker off for 30 seconds and retry.

Tools Required for Diagnosis

Multimeter (VAC and resistance settings)Manometer (for gas pressure testing, technician tool)ScrewdriversPipe wrench (for gas line connections, technician only)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

1

Locate the manual gas shutoff valve on the gas supply pipe

Locate the manual gas shutoff valve on the gas supply pipe leading to the furnace. It is typically a yellow-handled ball valve or a lever valve. Confirm it is in the fully open position (handle parallel to pipe = open). Also check that the gas meter at the home's exterior has not been shut off.

2

With the furnace attempting to start a heating cycle

3

With power off and gas shutoff closed

4

Inspect the wiring harness from the control board to the gas valve

5

If you have access to a manometer or know a technician who can

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name
Carrier Gas Valve (Natural Gas)EF32CW194 · $85–$175

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs
Labor Approach
Our Verdict
REPAIR
Estimated Cost: $130 (Parts) vs $2750 (New Machine)

Frequently Asked Questions

Can I replace a Carrier gas valve myself?
Gas valve replacement involves disconnecting and reconnecting gas lines and requires a leak test with a manometer or soap solution after installation. Most jurisdictions require this work to be performed by a licensed HVAC technician or gas fitter. The risk of a gas leak from an improper connection is a serious safety hazard. Hire a professional for this repair.
What does 24VAC at the gas valve terminals mean?
The control board sends 24 volts AC to the gas valve solenoid as the command signal to open the valve and allow gas flow. If you measure 24VAC at the valve terminals during a heating cycle but the valve does not open, the valve body is mechanically or electrically failed and needs replacement. If there is no 24VAC signal, the issue is upstream at the control board or wiring.
How do I know if my gas supply is the problem and not the valve?
If other gas appliances in the house (water heater, range, gas dryer) are working normally, the utility supply is likely fine. The most common supply-side issue specific to the furnace is the manual shutoff valve behind or beside the furnace being partially closed. Confirm it is fully open. A technician can measure inlet gas pressure at the valve test port to confirm normal supply pressure (3.5 inches WC for natural gas).
Why does Code 31 sometimes clear after resetting and then come back?
An intermittent Code 31 often points to a gas valve that is mechanically sticking but still opens occasionally, a wiring harness with an intermittent connection that vibration temporarily restores, or low gas pressure that fluctuates with utility demand. Intermittent faults are harder to diagnose and typically require live testing during a heating cycle to capture the fault in real time.
How much does it cost to replace a gas valve on a Carrier furnace?
The gas valve part itself costs $85-175 for most Carrier models. Labor for a licensed technician adds $150-300 depending on your area. Total repair cost typically runs $250-475. If the furnace is more than 15 years old, discuss with your technician whether replacement of the full unit makes more financial sense than a major component repair.

Related Carrier Furnace Error Codes

Code: HUBCarrier Furnace LED Flash Codes: Complete Fault Code GuideCode: 34Carrier Furnace Code 34: Ignition Proving FailureCode: RESETHow to Reset a Carrier Furnace and Clear LED Fault Codes

Models Known to Experience 31 Errors

This repair applies to most Carrier furnaces with this error code. Common model numbers include:

59TP6, 59MN7, 59SP5, 59TP6A, 58PAV

Last verified for technical accuracy on March 14, 2026