York Furnace Blink Codes: 1–9 Flashes — TM9V, YP9C, TG9S Diagnosis Guide

Common Symptoms

• Control board LED blinking a repeated counted flash sequence
• Furnace not heating — locks out before or during ignition
• Furnace tries to start and shuts off within 1–2 minutes
• Inducer motor runs but ignition never starts
• Red button on rollout switch has popped out and furnace won't start
• Furnace completely dead — LED shows 1 blink indicating normal with no previous faults

Most Likely Causes

1. 1

   2 Blinks — System Lockout

   The York control board attempted the ignition sequence the maximum number of times without successfully proving a flame and entered hard lockout. The furnace will not attempt ignition again until manually reset by power cycling. The 2-blink code points to the ignition system — failed igniter, oxidized flame sensor, gas pressure issue, or gas valve fault. Diagnose the ignition system before resetting the lockout, or it will return immediately.

2. 2

   3 Blinks — Pressure Switch Fault

   The draft inducer pressure switch did not close (or closed at the wrong time) during startup. On York furnaces, the first verification step is confirming the inducer is actually spinning — listen for the inducer fan to start within 30 seconds of a heat call. A weak or failed inducer on York TM9V and YP9C models is a common source of 3-blink codes that can be misdiagnosed as a switch failure. Beyond inducer verification, check the pressure hose for kinks and condensate blockage. On YP9C and TM9V 96% AFUE models, inspect the secondary condensate drain — a blocked drain causes condensate backup that prevents adequate inducer suction.

3. 3

   4 Blinks — Open Limit Circuit

   The high-temperature limit switch or another safety device in the limit circuit has opened. The heat exchanger overheated and tripped the limit. Primary cause: clogged air filter. Secondary causes: blocked return air grille, failed blower motor, or closed supply registers. York furnaces use a string of limit devices in series — the high-limit switch, roll-out switch, and in some models a duct high-limit — any one in the string can cause a 4-blink code. If the filter is clean and limits keep tripping, check each limit device individually for continuity.

4. 4

   5 Blinks — Flame Rollout Detected (Requires Manual Reset)

   The flame rollout switch has tripped — flames extended outside the normal combustion zone inside the burner box and activated the safety switch. This is a serious fault. The rollout switch on York furnaces has a red manual reset button in the burner box — the furnace will not operate until this button is physically pressed. More importantly, the cause of rollout must be found or it will trip again immediately. Rollout causes: a blocked flue or heat exchanger causing combustion gases to back up into the burner area, a cracked heat exchanger allowing combustion gas leakage, gas pressure too high, or an oversized burner that produces more heat than the heat exchanger can handle. Never reset a rollout without finding the cause — repeated rollout indicates a serious combustion safety issue.

5. 5

   8 Blinks — Ignition Failure

   The York furnace completed the inducer startup and pressure switch steps but failed to establish a flame during the trial for ignition period. Unlike the 2-blink system lockout (which fires after multiple retries), 8 blinks indicates the ignition sequence itself failed. Causes: a failed hot surface igniter (part S1-02532127000 is the York OEM igniter — test resistance, should read 40–90 ohms), an oxidized flame sensor, or gas valve not opening when commanded. Check the gas supply manually at the manifold — confirm the manual shutoff valve is fully open and the pilot light on your gas meter is lit.

6. 6

   9 Blinks — Flame Failure After Establishing (Gas Valve or Sensor Issue)

   The furnace successfully established a flame at startup but the flame died during normal operation — not during ignition trial. The board confirmed ignition but then lost the flame signal during the heating cycle. Causes: a gas valve coil weakening and closing intermittently during a heat cycle (test coil resistance — healthy York gas valve coils read 20–60 ohms), a flame sensor producing an adequate signal at startup but dropping below threshold as the sensor heats up (a sensor near failure), or unstable gas pressure during high-demand periods. This is different from 2-blink and 8-blink codes because the flame was established first.

Quick DIY Checks

1. 1Count the blink code: look through the observation window on the lower access panel to see the control board LED. Count flashes before the pause: 1 blink (normal, no previous fault stored), 2 blinks (system lockout), 3 blinks (pressure switch), 4 blinks (open limit), 5 blinks (flame rollout — look for popped rollout reset button), 6 blinks (115V polarity reversed), 7 blinks (low voltage below 18V), 8 blinks (ignition failure), 9 blinks (flame failure after establishing). Count through at least two complete sequences. On Coleman, Luxaire, and Champion units, these same codes apply identically — the Johnson Controls board is the same across all these brands.
2. 2For 5-blink flame rollout — the most important step: locate the rollout switch(es) in the burner compartment. On York TM9V and YP9C furnaces, the rollout switches are mounted on the burner box on each side of the burner manifold. Look for a red button that has popped out — this is the manual reset. Before pressing it: inspect the burner box for scorch marks, heat discoloration outside the normal flame path, or any sign that flames extended sideways or upward into the burner compartment. With a flashlight, look at the heat exchanger opening directly above the burners — any orange discoloration or warping indicates sustained rollout. Check the flue pipe connection at the furnace — ensure it is secure, unblocked, and not crushed. Also verify the main gas shutoff is not partially closed (check gas pressure at the manifold with a manometer if available). Only press the rollout reset button after the above checks — push the red button firmly until it clicks in. If it trips again within the first heat cycle, call for professional heat exchanger inspection before further operation.
3. 3For 3-blink pressure switch on York — verify inducer operation first: stand near the furnace and initiate a heat call at the thermostat. Within 30 seconds you should hear a distinct fan spinning up inside the furnace (the inducer motor). Listen carefully — a humming sound that starts and immediately sounds labored or rattling may indicate the inducer wheel is dirty or the motor bearings are worn. If you do not hear the inducer start at all, the issue may be the inducer itself rather than the pressure switch. After confirming the inducer sounds normal, trace the pressure hose for kinks and condensate blockage, blow it clear, and test the switch with suction. On YP9C 96% AFUE models, also check the condensate trap — a blocked York condensate trap is a common source of 3-blink codes on high-efficiency units.

1. 4For 8-blink ignition failure: power cycle the furnace (power off 30 seconds, power on) to clear the lockout. Watch through the sight glass as the startup sequence runs — in order: (1) inducer starts (fan sound), (2) pressure switch closes (no change visible, but happens 30 seconds in), (3) igniter warms up (glow visible through sight glass, approximately 40–60 seconds in), (4) gas valve opens and flame lights (blue/orange flame visible). If the igniter glows brightly but no flame appears, the gas valve is not opening — check the gas shutoff valve is fully open and test gas valve coil resistance (20–60 ohms). If no glow appears, test the York igniter S1-02532127000 — OL on the ohmmeter means it is cracked and needs replacement.
2. 5For 4-blink open limit circuit: replace the air filter and let the furnace cool for 20–30 minutes before attempting restart. If 4 blinks returns with a fresh filter and the blower is running normally, test each limit device in the limit circuit for continuity. With the furnace off and cold, set the multimeter to continuity mode and probe across each limit switch's two terminals. A cold limit switch should show continuity (beep). Any limit showing OL when the furnace is cold has failed in the open position and needs replacement. Common York limit switch locations: main high-limit on the heat exchanger, rollout limit in the burner box, and on high-efficiency models an auxiliary limit on the secondary heat exchanger.
3. 6Lockout reset for York: set the thermostat to OFF. Flip the furnace power switch to OFF and wait 30 seconds. Restore power, then call for heat with the thermostat at least 5°F above room temperature. For 5-blink rollout codes, you also need to manually press the red rollout switch reset button in the burner box before power cycling — the rollout switch is a non-automatic reset device on York furnaces and the furnace will not start until it is pressed regardless of power cycling. After resetting, monitor the first full heat cycle carefully — inducer start, igniter glow, flame establishment, and sustained burner operation through the call for heat.

Repair vs Replace

Recommended Tools & Parts

• York Hot Surface Igniter (S1-02532127000)

  OEM York replacement hot surface igniter for TM9V, YP9C, TG9S, YP8C, and LX series furnaces. Also compatible with Coleman, Luxaire, and Champion furnaces sharing the York Johnson Controls platform. Fixes 8-blink ignition failure code.

  $25–$65

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• York Flame Sensor Rod

  Replacement flame sensor for York, Coleman, Luxaire, and Champion gas furnaces. Fixes 9-blink flame failure after establishing and persistent 8-blink ignition failure after igniter tests good. Match the mounting bracket style to your existing sensor.

  $15–$35

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• York Draft Inducer Pressure Switch

  Replacement pressure switch for York, Coleman, Luxaire, and Champion furnaces. Fixes 3-blink pressure switch fault when hose and condensate drain are verified clear. Match the water column (WC) rating on your existing switch.

  $20–$55

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• York Furnace Rollout Limit Switch

  Replacement manual-reset rollout limit switch for York TM9V, YP9C, TG9S and compatible Coleman/Luxaire furnaces. Fixes 5-blink rollout code when the rollout switch itself has failed and will not hold reset after root cause is corrected. Match the temperature rating on your existing switch.

  $15–$40

  Buy on Amazon →

Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.

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