York Furnace Error Codes

An HVAC brand under Johnson Controls, manufacturing residential and commercial heating systems.

Disclaimer
This site is not affiliated with or endorsed by York or Johnson Controls.

How York Furnaces Display Error Codes

The furnace has built-in, self-diagnostic capability. A blinking LED light on the control board can flash red, green or amber to indicate various conditions. The SLOW flash speed is two seconds on and two seconds off. The other flash codes turn on for 1/3 second and off for 1/3 second, repeated the number of times equal to the code, with a two-second pause between codes. The continuous flash codes flash the LED on and off continuously, with no breaks or longer pauses.

This site covers 2 York furnace models and a total of 36 error code entries. Select your model below to see the full code list with causes and repair guidance.

York Furnace Models

Model Type
TM9T100C16MP11 Two Stage Gas Furnace →
TM9V080B12MP11 Single Stage Gas Furnace →

DIY-Friendly York Error Codes

These error codes on York furnaces are commonly resolved by a careful homeowner without a service call — typically by cleaning the flame sensor, checking filters, or inspecting the exhaust vent. Always turn off power and gas before attempting any repair.

Code Fault Models
4 Amber Flashes Y Signal Without G Signal 2 models

High-Severity York Error Codes

These codes indicate conditions that prevent normal furnace operation or involve safety-relevant components such as the gas valve, heat exchanger, or inducer motor. Most require a licensed HVAC technician to diagnose and repair safely.

Code Fault Models
Steady On (Any Color) Control Failure 2 models
8 Red Flashes Flame Lost Five Times (Recycle) 2 models
1 Red Flash Flame Sensed Without Call for Heat 2 models
10 Red Flashes Gas Valve Energized Without Call for Heat 2 models
7 Red Flashes Ignition Failure - No Flame Detected 2 models
11 Red Flashes Limit Circuit Open 5-15 Minutes 2 models
5 Red Flashes Limit Circuit Open Over 15 Minutes 2 models
4 Red Flashes Main Limit Switch Open 2 models

About York

York is one of the oldest names in the HVAC industry, tracing its origins to a company started in York, Pennsylvania, in 1874. Over more than a century of operation, the brand grew to become the world's largest independent manufacturer of air conditioning, heating, and refrigeration machinery before its acquisition by Johnson Controls.

Johnson Controls purchased York International in 2005 for $3.2 billion. Following the acquisition, York was integrated into Johnson Controls' Building Technologies and Solutions division. Johnson Controls International plc, the parent company, was itself founded in 1885 by Warren S. Johnson, who received a patent for the first electric room thermostat in 1883. As of fiscal year 2025, Johnson Controls reported revenue of $23.6 billion and employed approximately 87,000 people worldwide, with headquarters in Cork, Ireland.

York in the Furnace Market

York serves both the residential and commercial HVAC markets under Johnson Controls' building technology portfolio. The residential product line includes furnaces, air conditioners, and heat pumps; commercial offerings span air systems, chilled water systems, packaged and split DX systems, and ductless and VRF systems. York products are manufactured at Johnson Controls' Wichita, Kansas facility alongside the Coleman brand, sharing production resources. The brand distributes through certified dealer and contractor networks and participates in energy efficiency incentive programs.