If your York furnace is flashing a light on the control board behind the blower door, the first thing to notice is the color — because on York, the color changes the meaning. York, along with its Coleman and Luxaire sister brands (all on Johnson Controls boards), uses a red LED for fault codes, an amber LED for airflow and venting conditions, and green for normal operating states. Count the flashes and note the color, or you'll read the wrong chart.
Reading the code: note the LED color first, then count the flashes between pauses. Red is a fault, amber is an airflow/venting condition, green is normal. Flash-code meanings can vary by control-board generation, so always confirm the color and count against the diagnostic label inside your unit — printed inside the blower-compartment door — before you buy a part.
York red flash codes (faults)
| Red flashes | Meaning | Typical cause |
|---|---|---|
| 1 | Flame sensed with no call for heat | A leaky or slow-closing gas valve |
| 2 | Pressure switch stuck | A stuck or welded switch or contacts |
| 3 | Pressure switch won't close / draft issue | A weak inducer, a blocked vent or flue, or a condensate backup |
| 6 | Pressure switch opened 4x → 1-hour lockout | Repeated venting or inducer restriction during the cycle |
| 7 | Ignition lockout — no flame after 3 tries | Low gas, a gas-valve issue, a dirty flame sensor, or a bad hot-surface igniter |
| 8 | Flame lost 5x during a cycle | Dirty flame sensor, a marginal flame, or gas-supply dropouts |
York amber flash codes (airflow & venting)
| Amber flashes | Meaning | Typical cause |
|---|---|---|
| 4 | Restricted circulating (indoor) air | Dirty filter, blocked returns, or restricted ducts |
| 5 | Restricted vent / combustion air | A blocked intake or exhaust, or poor combustion-air supply |
| Rapid amber | Possible low flame signal | A weak or dirty flame sensor, or a lazy flame |
| 3 amber | Normal end of heating cycle | Not a fault — this is a normal shutdown indication |
A steady or slow green flash is York's way of showing normal operating states (power on, call for heat, and so on) — green is not a fault.
About codes 6 through 9 and E/F/P codes
Two cautions before you act on a York chart:
- Codes 6 through 9 differ by board generation. Newer UTEC boards and older White-Rodgers / Texas Instruments / 50A5x-style boards don't number the higher codes the same way, so a "6" or "8" on one generation isn't guaranteed to mean the same thing on another. Verify the code on your specific board and against the diagnostic label inside your unit rather than trusting a generic chart.
- York E, F, and P codes are NOT central-furnace codes. Those alphanumeric codes belong to York ductless mini-split and PTAC equipment, not gas furnaces. If you're reading an "E" or "P" code, you're looking at the wrong chart for a furnace — don't conflate the two.
Where a chart and your board disagree, the label on your furnace is the authority.
Common causes
Across the red and amber codes above, most common first:
- Dirty filter or restricted ducts — the amber 4, and a frequent background cause.
- Dirty flame sensor — behind a red 7 lockout, a red 8, or a rapid-amber low-flame signal.
- Blocked vent, clogged condensate, or a weak inducer — behind red 2, 3, and 6 and the amber 5.
- Failed hot-surface igniter or a gas-valve issue — the harder end of a red 7.
- A leaking gas valve — the unusual red 1, flame with no call.
The usual fix
Our tech reads the color and count, then confirms it: check and change the filter, clean or replace the flame sensor and measure the flame signal, verify the inducer and venting draw properly, test the pressure and limit switches, and inspect the igniter and gas pressure. On a red 1 (flame with no call) or repeated flame-loss codes, we check the gas valve and combustion carefully. A cleaned sensor or restored airflow clears many York calls; when a part has truly failed, we replace it and confirm a full, clean heat cycle.
DIY vs. calling a pro
Safe to try yourself first (free):
- Turn the furnace off and change a dirty filter, wait 20–30 minutes, and restart — this clears a large share of amber 4 airflow codes.
- Open blocked supply and return vents and clear anything sitting over a return.
- Power-cycle at the switch or breaker to reset a soft lockout after fixing airflow.
Call a pro when:
- You see a red 7 ignition lockout or a red 6 one-hour lockout that won't clear.
- A red 1 (flame sensed with no call) appears — a leaking gas valve is a safety issue, not a reset.
- A code returns after a fresh filter, or you smell a hot or burning odor.
Gas, line-voltage electrical, and any refrigerant or compressor work belong with a licensed technician (EPA 608 certified for refrigerant handling). A furnace with a suspected gas-valve leak, rollout, or a heat-exchanger problem can be a carbon-monoxide risk and should be shut off until it's inspected.
What it costs in the Bay Area
Many York codes resolve with a filter or a cleaned flame sensor. When a part is needed, in our pricing a flame sensor runs about $90–$250, a hot-surface igniter $120–$350, and a control board $200–$600, depending on the model. We charge a diagnostic fee that's credited toward the repair when you approve the work, with a firm, upfront price before any work begins.
Book York furnace service
Triton services York, Coleman, and Luxaire furnaces — plus every major brand — across the SF Bay Area & Peninsula, with same-week and often same-day appointments. If your York is flashing red or amber, we'll read the color and count correctly, verify it on the unit, and get your heat back safely.
Call (888) 993-5699 or book online for same-day furnace service.
Related pages
- HVAC Repair in the SF Bay Area — our full heating & cooling hub
- Furnace Not Heating / No Heat — the symptom behind a red or amber code
- Furnace Won't Ignite / No Ignition — the symptom behind a red 7 lockout
- Rheem Furnace Error Codes (Blinking Light Guide) — flash codes on another brand
- Lennox Furnace Error Codes (E200, E250 and More) — alert codes on another brand
- Furnace Repair in Redwood City — same-day service in your city
Frequently asked questions
What does the light color mean on my York furnace? On York, Coleman, and Luxaire furnaces the color changes the meaning. Red flashes are fault codes such as an ignition lockout or a pressure-switch fault, amber flashes are airflow and venting conditions such as a restricted filter or vent, and green indicates normal operating states. Always note the color before counting the flashes.
What does a red 7 flash mean on a York furnace? A red 7 is an ignition lockout: the furnace failed to establish flame across three tries and stopped for safety, so you have no heat. It is usually a dirty flame sensor, a weak hot-surface igniter, low gas, or a gas-valve issue. You can power-cycle once after checking the gas is on, but a lockout that returns should be diagnosed.
What does an amber flash mean on a York furnace? Amber flashes are airflow and venting conditions rather than hard faults. Amber 4 is restricted circulating air, usually a dirty filter or blocked ducts, and amber 5 is restricted vent or combustion air. Note that a 3-amber flash is the normal end-of-cycle indication and not a fault at all.
Are York E1, E2, or P codes furnace error codes? No. York E, F, and P alphanumeric codes belong to York ductless mini-split and PTAC equipment, not gas furnaces. If you are reading a letter code, you are on the wrong chart for a furnace. York furnaces use red, amber, and green flash counts on the control board.
Why do York codes 6 through 9 not match the chart I found? Because they differ by board generation. Newer UTEC boards and older White-Rodgers, Texas Instruments, and 50A5x-style boards number the higher codes differently, so the same count can mean different things. Verify the code on your specific board and against the diagnostic label inside your unit before buying a part.
How much does York furnace repair cost in the Bay Area? Many codes resolve with a filter or a cleaned flame sensor. When a part is needed, a flame sensor runs about 90 to 250 dollars, a hot-surface igniter 120 to 350 dollars, and a control board 200 to 600 dollars in our pricing, depending on model. We credit the diagnostic fee toward the repair and quote a firm price first.