It's a crisp September evening in Aurora — maybe you're near Saddle Rock or over by Tallyn's Reach — and you crank the heat on for the first time since last spring. Nothing. Just cold air blowing through the vents. You head down to the mechanical room, crouch in front of the furnace, and realize the pilot light is out. Again. You relight it, hold the button, count to 30, let go... and the flame dies. That moment of frustration is something we've seen play out in hundreds of Aurora homes, and honestly, it's one of the most common furnace repair calls we get every fall when temperatures in the Denver metro start doing that classic Colorado thing where it's 75°F at noon and 38°F by midnight.
Why Your Furnace Pilot Light Won't Stay Lit — The Real Reasons
Let's skip the vague stuff and talk about what's actually happening. When a furnace pilot light won't stay lit, there are really only a handful of culprits, and most of them are pretty straightforward once you know what to look for.
A Dirty or Failing Thermocouple
This is the number one cause, full stop. The thermocouple is a small safety device — a metal rod that sits right in the pilot flame. When it's heated by the flame, it generates a tiny electrical signal that tells the gas valve "hey, the flame is on, it's safe to keep the gas flowing." When the thermocouple is dirty, bent out of position, or just worn out, it can't generate that signal reliably. The gas valve closes. The flame dies. You're back to square one.
Aurora homes that were built in the late 90s through mid-2000s — and there are a lot of them — often have furnaces that are now 20+ years old. Thermocouples on those units have had a long run. They don't last forever. A replacement thermocouple typically costs $15-$30 for the part itself, and it's something a handy homeowner can swap out, though we'll talk more about that shortly.
Dirty Pilot Orifice
Colorado's air is dry — genuinely, unusually dry — and dust accumulates in ways that homeowners from more humid climates never expect. That tiny pilot orifice can get partially clogged with dust and debris, especially if the furnace sat unused all summer. A weak, flickering pilot flame often can't generate enough heat to properly activate the thermocouple, even if the thermocouple itself is fine.
Low Gas Pressure or a Draft Issue
Here's something specific to our area: altitude matters. Aurora sits at roughly 5,500 feet above sea level, and gas appliances can behave differently at elevation than they would in, say, Kansas City. Gas pressure that's slightly off spec can cause a marginal pilot situation that just barely works in summer but fails when the furnace is cold-starting in fall. Also, older homes sometimes have combustion air issues — drafts sneaking in through gaps can literally blow the pilot out, especially in a drafty utility closet.
A Faulty Gas Valve
Less common, but it happens. The gas valve itself can fail or stick, causing intermittent gas supply to the pilot. This one usually requires a professional diagnosis because gas valve replacement is not a DIY job.
How to Diagnose What's Going On With Your Pilot Light
Before you call anyone, here are a few things worth checking yourself — safely.
- Check the pilot flame color and size. A healthy pilot flame should be a steady blue with maybe a small yellow tip, and it should visibly engulf the tip of the thermocouple rod. If the flame is tiny, orange, or flickering wildly, you've got a weak pilot situation — likely a dirty orifice or low gas pressure.
- Check the thermocouple position. Look at where the thermocouple tip sits relative to the pilot flame. It should be right in the hottest part of the flame. If it's been bumped or has drifted, carefully bend it back into position. Sometimes that's literally the whole fix.
- Try the relight procedure correctly. Push and hold the pilot button fully for a full 45-60 seconds after lighting — not just 30. The thermocouple needs time to heat up enough to signal the valve. A lot of people give up too early.
- Look for obvious dirt or debris. If you can see dust buildup around the pilot assembly, that's a clue. A can of compressed air can sometimes clear a partially blocked orifice, though be careful and make sure the gas is off first.
- Note how quickly the flame dies. Does it go out immediately when you release the button? That's almost always thermocouple. Does it stay lit for a few minutes then die? Could be a draft, a weak flame, or a more complex issue.
What This Repair Costs in the Aurora Area
Let's be direct about money, because nobody likes vague estimates.
If it's just a thermocouple replacement — the most common fix — you're typically looking at $100-$175 for a professional repair including labor and the part. If a tech has to clean the pilot assembly and adjust the thermocouple position in addition, maybe $150-$200 total. A gas valve replacement is more involved: parts alone can run $75-$200 depending on the valve, and total repair cost with labor usually lands between $300-$500.
Now, here's the honest conversation: if your furnace is over 18-20 years old and you're looking at a gas valve replacement, it's worth having a real discussion about whether repair or replacement makes more financial sense. A new furnace with modern efficiency ratings — especially relevant in Colorado where heating costs are real — can pay back the investment faster than you'd think. We're not going to push you toward replacement if repair makes sense, but we'll give you the straight answer either way.
Most furnace repair calls in Aurora get resolved in a single visit, usually under two hours. Fall is busy season, so if you're dealing with this right now, don't wait — call (720) 227-6636 and we'll get you on the schedule fast.
DIY vs. Calling a Pro — An Honest Take
We believe in being straight with people. Some of this you can handle yourself. Some of it you really shouldn't touch.
Reasonable DIY territory: Relighting the pilot following the manufacturer's procedure. Cleaning visible dust from the pilot area with compressed air (gas off, of course). Gently repositioning a thermocouple that's visibly out of place. Replacing a thermocouple if you're mechanically comfortable — it's usually just a couple of screws and a fitting, and YouTube tutorials exist for most furnace models.
Call a professional for: Anything involving the gas valve. Any situation where you smell gas — leave the house and call 911 and your gas company first, then us. Any repair where you're not 100% confident in what you're doing. Annual furnace tune-ups (seriously, get one every fall before you need heat). And honestly, if you've tried the DIY steps above and the pilot still won't hold, it's time for professional eyes on it.
One more thing specific to Colorado: our dry climate and altitude create combustion conditions that differ from what the manufacturer's engineers might have been optimizing for. Subtle tuning adjustments sometimes make a real difference up here, and that's the kind of thing an experienced local tech catches that a national chain tech rushing through calls might miss. You can also check out our furnace repair services page to learn more about what a full diagnostic visit covers.
Why a Local Aurora-Area Company Makes a Difference Here
Highlands Ranch Heating & Air has been working in the Denver south metro for years. We know Aurora. We know the subdivisions, the home ages, the common equipment brands installed during the big building booms of the late 90s and early 2000s. We've been inside mechanical rooms from Centennial to Castle Rock, from Lone Tree condo complexes to Parker acreage properties with older systems that need a careful hand.
That local knowledge actually matters. When a tech from our team shows up at an Aurora home, they're not guessing about whether the altitude might be affecting combustion or whether a particular neighborhood era of homes tends to have certain furnace brands with known thermocouple quirks. They've just... seen it before. A lot.
We're also not a call center operation. When you call (720) 227-6636, you're reaching a team that actually serves this community. We do furnace repair, maintenance, full system replacements, and — when summer eventually comes back around — AC repair too. One company, year-round, people who know your neighborhood.
If your furnace pilot light won't stay lit this fall, don't spend the night in a cold house. Give us a call or visit highlandsranchheatingandair.com to schedule service. We'll figure out exactly what's going on and give you an honest recommendation — whether that's a $20 thermocouple or a bigger conversation about your system's future.
Frequently Asked Questions
Is it safe to keep relighting my furnace pilot light if it keeps going out?
Relighting the pilot a couple of times while troubleshooting is generally safe, as long as you follow the proper procedure — waiting a full minute between attempts to allow any residual gas to dissipate, and never relighting if you smell gas. However, if you're relighting it daily or multiple times a week, that's not a normal situation and you should have a technician look at it. Repeatedly losing the pilot flame usually indicates a component problem that won't fix itself, and it's better to get it diagnosed than to keep manually relighting it indefinitely.
How long should a thermocouple last in a Colorado furnace?
In typical use, a thermocouple should last anywhere from 7-12 years, though we've seen them last longer and fail sooner. Colorado's dry air and the altitude-related combustion conditions can be mildly harder on components than more moderate climates. If your furnace is over 15 years old and you're having pilot issues, the thermocouple is often one of the first things to suspect. The good news is it's one of the cheaper fixes in the furnace repair world.
My pilot light stays on but the furnace still doesn't heat — what's going on?
This is a different issue than a pilot that won't stay lit. If the pilot is burning but the main burner won't ignite or the furnace isn't producing heat, the problem is likely elsewhere — could be the main gas valve, the thermostat, a limit switch that's tripped, or a control board issue on newer systems. This situation really does warrant a professional diagnostic visit, because there are several possible causes and some of them (like a tripped high-limit switch) can indicate a more serious underlying problem like restricted airflow.
Should I replace my older Aurora furnace instead of repairing the pilot light?
It depends on the furnace's age, overall condition, and the cost of the repair. For a simple thermocouple replacement on a furnace that's otherwise in good shape and under 18 years old, repair almost always makes sense. If the furnace is 20+ years old and you're looking at a gas valve replacement or other significant repair, it's worth getting an honest assessment of the whole system. Modern furnaces run at 95%+ efficiency versus the 60-70% efficiency of older units — in Colorado's climate where you're running heat from October through April, that efficiency difference adds up fast on your Xcel Energy bill.
Can altitude in Aurora affect my furnace's pilot light performance?
Yes, it can be a factor, though it's usually minor with a properly maintained system. At Aurora's elevation of around 5,500 feet, the air is less dense, which affects combustion slightly. Gas appliances installed in Colorado are typically deorificed (have smaller orifices) at the factory or during installation to account for this. However, if a furnace was ever swapped in without proper altitude adjustment, or if gas pressure is on the low end of spec, you can get marginal pilot situations that cause intermittent problems. A good local technician will check gas pressure and combustion conditions as part of any thorough furnace diagnostic.
How quickly can Highlands Ranch Heating & Air get to Aurora for a furnace repair?
We serve Aurora regularly and typically can schedule service calls within 1-2 business days, often sooner depending on our schedule. During peak fall heating season — September and October especially — things get busy fast across the Denver south metro, so we always recommend calling sooner rather than later if you're having issues. For urgent situations where you have no heat, call us at (720) 227-6636 and explain the situation — we do our best to prioritize no-heat calls, especially when overnight temperatures are dropping.