Quick diagnosis
What this code is telling you
Most likely trigger
Dirty or oxidized flame sensor rod
Recommended replacement
Furnace Flame Sensor Rod
Diagnostic path
4 ordered checks
Part fit
Exact model number required
Safety first
Before opening the appliance
Unplug the appliance before removing panels or testing internal components. Do not bypass safety switches or live-test high-voltage, gas, refrigerant, or combustion components unless you are qualified to do so.
Read the full safety disclaimerRoot cause
Why the control reported this error
The heat-pump control reports this fault when a monitored pressure, temperature, communication, or compressor condition is abnormal. Begin with dirty or oxidized flame sensor rod; also verify closed gas supply shutoff valve and hot surface igniter cracked or open circuit before replacing furnace Flame Sensor Rod.
Symptoms
What you may notice
- ✓Heat pump or furnace tries to start 3 times then shuts down
- ✓System locked out for 1 hour
- ✓Red light flashes twice repeatedly
Possible causes
Check the most likely causes first
- 1
Dirty or oxidized flame sensor rod
Start here when it matches your symptoms.
- 2
Closed gas supply shutoff valve
- 3
Hot surface igniter cracked or open circuit
- 4
Defective gas valve solenoid
Diagnostic sequence
Work through these checks in order
Stop when you find the fault. Do not perform a step that requires skills or live testing you are not qualified to do.
- 1
Check 1
Clean metal flame sensor rod gently with fine steel wool or emery cloth.
- 2
Check 2
Disconnect electrical power before opening panels. Ensure main gas valve knob is turned fully on.
- 3
Check 3
Disconnect electrical power before opening panels. Check hot surface igniter for visible cracks or measure resistance.
- 4
Check 4
Replace flame sensor assembly.
Replacement part reference
Furnace Flame Sensor Rod
Exact OEM part number
Model number required
Fitment note
The exact OEM part number varies by model and production revision. Verify the complete model number before ordering.
Verify the appliance model before ordering.
Manufacturers can use different parts under the same error code across model families and production revisions.
Where do I find my model number? →FixCodeDB may earn a commission from qualifying purchases made through affiliate links.
Common questions
Quick answers for this fault
What should I check first for 2 Flashes?
Start with dirty or oxidized flame sensor rod. If that checks out, continue through the diagnostic sequence above rather than replacing a part based on the code alone.
Does 2 Flashes always mean Furnace Flame Sensor Rod is bad?
No. An error code identifies the condition the control detected, not a guaranteed failed part. Confirm the likely causes and wiring first. The exact OEM part number varies by model and production revision. Verify the complete model number before ordering.
When should I stop troubleshooting 2 Flashes myself?
Stop if the next step requires live electrical testing, sealed-system work, gas or combustion service, or any procedure outside your training. Unplug the appliance before removing panels or testing internal components. Do not bypass safety switches or live-test high-voltage, gas, refrigerant, or combustion components unless you are qualified to do so.
Was this useful?
Did these checks help with your Trane 2 Flashes error?
Keep diagnosing
Related Trane guides
Different problem?
Search another code or symptom
Go back to the main diagnostic search and try the code, symptom, appliance, component, or brand.
Open diagnostic search →