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CODE-43

Carrier · Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower

Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower CODE-43 Error Fix: Infinity Code 43 — Low Flame Signal / Dirty Flame Sensor

The Infinity System Control displays "Code 43" indicating the flame signal from the furnace is below the acceptable threshold. This is the communicating-system equivalent of the rapid-flash LED code on standard furnaces. The Infinity system may display the actual flame signal strength in microamps. A clean flame sensor should produce 2-6 µA; below 1 µA triggers this code. The fix is almost always the same: remove and clean the flame sensor rod with fine emery cloth or steel wool. On Infinity modulating furnaces, Code 43 may appear only at certain modulation rates — at low fire, the smaller flame produces a weaker signal, and a partially dirty sensor that works at high fire may fail at low fire. The Infinity Control's fault log and real-time diagnostics can show flame signal history, making it easy for a technician to diagnose trending issues.

Medium severity2 fixes available

Quick Answer

Error CODE-43 on the Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower means: Infinity Code 43 — Low Flame Signal / Dirty Flame Sensor. The top-ranked community fix is “Replace the Flame Sensor Assembly” (medium difficulty, ~45 min, DIY cost: $15-$25). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · furnace

Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.

When to Call a Professional

While many furnace repairs can be done safely at home, consider hiring a qualified technician if:

The repair involves electrical wiring, gas lines, or refrigerant
You've tried the top-ranked fix and the error persists
You smell gas, see sparking, or notice water leaking
The repair requires specialized tools you don't have
Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $120-$180.

Other Carrier Models with Error CODE-43

Carrier 59MN7 Infinity 98 Modulating 98.5% AFUE Gas Furnace with Greenspeed Intelligence

furnace · 2 fixes

Other Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower Error Codes

CODE-21

Infinity Code 21 — Gas Heating Lockout

2 fixes

CODE-22

Infinity Code 22 — Abnormal Flame-Proving Signal

2 fixes

CODE-23

Infinity Code 23 — Pressure Switch Fault

2 fixes

CODE-24

Infinity Code 24 — Secondary Voltage Fuse Blown

2 fixes

CODE-26

Infinity Code 26 — Line Voltage Limit Circuit Open

2 fixes

CODE-41

Infinity Code 41 — Blower Motor Fault

2 fixes

CODE-42

Infinity Code 42 — Inducer Motor Fault

2 fixes

CODE-44

Infinity Code 44 — Blower Calibration Fault

2 fixes

People Also Ask About Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower Error CODE-43

What does error code CODE-43 mean on a Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower?

Error code CODE-43 on the Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower means: Infinity Code 43 — Low Flame Signal / Dirty Flame Sensor. The Infinity System Control displays "Code 43" indicating the flame signal from the furnace is below the acceptable threshold. This is the communicating-system equivalent of the rapid-flash LED code on standard furnaces. The Infinity system may display the actual flame signal strength in microamps. A clean flame sensor should produce 2-6 µA; below 1 µA triggers this code. The fix is almost always the same: remove and clean the flame sensor rod with fine emery cloth or steel wool. On Infinity modulating furnaces, Code 43 may appear only at certain modulation rates — at low fire, the smaller flame produces a weaker signal, and a partially dirty sensor that works at high fire may fail at low fire. The Infinity Control's fault log and real-time diagnostics can show flame signal history, making it easy for a technician to diagnose trending issues.

How do I fix error code CODE-43 on my Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower?

The most successful fix is "Replace the Flame Sensor Assembly" (medium difficulty, ~45 minutes). Estimated DIY cost: $15-$25. HomeMD has 2 community-ranked fixes for this error.

Is error code CODE-43 on a Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower serious?

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Can I fix Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower error CODE-43 myself?

Yes — the top-ranked community fix ("Replace the Flame Sensor Assembly") is rated medium difficulty and takes about 45 minutes. Tools needed: 1/4 inch nut driver, Multimeter (optional).

How much does it cost to repair Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower error CODE-43?

DIY cost: $15-$25. Professional repair typically costs $120-$180. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower have?

The Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower has 8 other known error codes, including: CODE-21 (Infinity Code 21 — Gas Heating Lockout), CODE-22 (Infinity Code 22 — Abnormal Flame-Proving Signal), CODE-23 (Infinity Code 23 — Pressure Switch Fault), CODE-24 (Infinity Code 24 — Secondary Voltage Fuse Blown), CODE-26 (Infinity Code 26 — Line Voltage Limit Circuit Open), and 3 more.

Which other Carrier models have the CODE-43 error?

Error code CODE-43 also appears on 1 other Carrier model: Carrier 59MN7 Infinity 98 Modulating 98.5% AFUE Gas Furnace with Greenspeed Intelligence. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower have?

The Carrier Carrier 59TN6 Infinity 96 Two-Stage 96% AFUE Gas Furnace with Variable-Speed Blower has 8 other known error codes:

CODE-21 — Infinity Code 21 — Gas Heating Lockout (2 fixes)
CODE-22 — Infinity Code 22 — Abnormal Flame-Proving Signal (2 fixes)
CODE-23 — Infinity Code 23 — Pressure Switch Fault (2 fixes)
CODE-24 — Infinity Code 24 — Secondary Voltage Fuse Blown (2 fixes)
CODE-26 — Infinity Code 26 — Line Voltage Limit Circuit Open (2 fixes)
CODE-41 — Infinity Code 41 — Blower Motor Fault (2 fixes)
CODE-42 — Infinity Code 42 — Inducer Motor Fault (2 fixes)
CODE-44 — Infinity Code 44 — Blower Calibration Fault (2 fixes)

Which other Carrier models have the CODE-43 error?

Error code CODE-43 also appears on 1 other Carrier model:

Carrier 59MN7 Infinity 98 Modulating 98.5% AFUE Gas Furnace with Greenspeed Intelligence (furnace) · 2 fixes

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