KeepRite Furnace error codes & fault diagnosis in Greater Vancouver

The call usually comes in the same shape. No heat, and a small light behind the furnace door doing something rhythmic. Three flashes, pause, three flashes. The homeowner has already found four different meanings for it online, all from different brands, all confident, none of them matching their furnace.

Here is the thing that gets missed: the code is a starting point, not a diagnosis. A given pattern tells you which safety or sensing circuit the control board is unhappy about. It does not tell you which of the six or seven components in that circuit is the cause. That is what a technician’s sequence of checks is for.

What follows is how to read the code off your own KeepRite furnace correctly, what each general fault family actually means physically, and where the line sits between what you can safely check and what needs a licensed gas technician. Gas appliances have that line for a reason, and we will be specific about it.

Read the code off your own furnace, not off the internet

Start at the furnace, not at a search bar. On most KeepRite gas furnaces the diagnostic indicator sits on the integrated control board in the lower compartment, and many models let you see it through a small sight glass in the door so you can watch it with the panel closed and the blower door switch still made. Some newer boards use a two-character alphanumeric display instead of a blink pattern.

If it is a blink code, timing carries meaning. Watch several full cycles before you decide what you saw. A pattern of two short flashes then three short flashes is not the same as five flashes. A steady-on light, a rapid continuous flicker, and a slow heartbeat are usually three different states, and one of them often just means “normal, no fault stored.” Write down what you observe, including the pause length, before touching anything.

Then find the legend. There is almost always a diagnostic chart printed on a label inside the furnace cabinet, on the inside of the door, or near the control board, and it applies to your exact model. That label outranks anything you read elsewhere.

One more habit worth having: note the code before you cut power. Cycling the breaker frequently clears stored fault history, and you have just erased the most useful piece of evidence a technician could have had.

Why the same flash pattern means different things on different furnaces

Manufacturers revise control boards. Across model families, production years and even mid-run board changes, the mapping between blink pattern and fault can shift, and a second-stage or variable-speed model will have codes a single-stage model never uses. Communicating systems that talk to a matched thermostat and outdoor unit add another layer of codes that describe the conversation between components, not the furnace itself.

This is exactly why we will not publish a table of specific code meanings. A homeowner who acts on the wrong table replaces a part that was fine, leaves the actual fault in place, and in the worst case defeats a safety device because a chart from a different appliance said the problem was elsewhere.

Use three sources in this order. First, the diagnostic label inside your furnace cabinet. Second, the installation and service manual for your specific model number, which you can pull from the rating plate. Third, a licensed technician who can put a manometer and a meter on the circuit and confirm what the board is reporting.

While you are at the rating plate, photograph it. Model number, serial number and the manufacture date make every subsequent conversation faster, and the serial usually tells us the production year, which is what determines which board revision you are dealing with. Have that ready when you call (604) 330-3812.

Ignition faults: what the board saw and did not see

Ignition-related faults describe a heating sequence that started and then stopped because the board never confirmed a proper light-off, or confirmed it several times and finally locked out. Physically, the furnace has to prove draft, energize the igniter, open the gas valve, and see flame within a short trial window. Fail that window enough times in a row and the control locks out deliberately, so unburned gas is not repeatedly dumped into a heat exchanger.

A technician works this in order because the order reflects the sequence. Is the inducer running and is draft actually being proven, or is the trouble upstream of ignition altogether? Does the igniter glow, and does it glow at the right point in the sequence? Is gas arriving, at the correct manifold pressure, with the shutoff open and the supply adequate for the whole appliance load? Is the burner assembly clean, and is the flame carrying across the burners the way it should?

What a homeowner can reasonably check: the gas shutoff valve is open, other gas appliances in the home are working, the furnace switch is on, and the thermostat is actually calling. That is the boundary.

Do not repeatedly reset a furnace that keeps locking out on ignition. The lockout is a safety function doing its job. Repeated resets keep introducing gas into a system that has already shown it will not light.

Flame sense faults: lights, then drops out

This family is different from failure to ignite, and the distinction matters. Here the burners light, you may even hear and see the flame, then a few seconds later the gas valve closes and the furnace shuts down, sometimes retrying, sometimes locking out. What failed is not combustion. It is proof of combustion.

A flame sensor works on flame rectification: a tiny current passes through the flame from the sensor rod to ground. That current is measured in microamps, which means it is fragile. A thin oxide film on the rod, a slightly moved sensor position, a weak ground path, corroded connections, or a flame that is lifting or lazy because of a burner or gas pressure issue can all drop the signal below the board’s threshold.

A technician measures the actual microamp reading against the acceptable range for that control, then decides whether the sensor needs cleaning and re-seating, whether the ground and wiring are the real problem, or whether the flame quality itself is off, which points back at burners, gas pressure or combustion air.

Sensor cleaning gets recommended online as a homeowner job. In British Columbia, work on gas-fired appliances falls under TSBC gas certification, and the fix that looks like polishing a rod frequently turns out to be a grounding or combustion problem. That is a technician visit, not a Saturday project.

Pressure, venting and condensate faults in a wet coastal climate

Before the gas valve is allowed to open, the furnace has to prove that the inducer is actually moving combustion products. A pressure switch senses that draft. If it does not close when expected, or closes when it should be open, the board reports a pressure or draft-related fault and refuses to proceed. That refusal is protecting you from spilling combustion gases into the house.

Our climate produces these calls in volume. A high-efficiency condensing furnace vents through plastic pipe to the outside, and Lower Mainland weather goes after those terminations: snow and slush drifting up over an intake, leaves and blown debris from a wet fall, wasp and bird nests built into an unscreened pipe over the summer, and on the worst nights, frost building at the termination itself. Sidewall terminations near ground level in a Surrey or Abbotsford side yard are the usual suspects.

The second half of this family is condensate. A condensing furnace makes acidic water and has to drain it. A plugged trap, a blocked drain line, a full or failed condensate pump, or a line that froze in an uninsulated crawlspace backs water up into places it does not belong and triggers a shutdown.

You can safely check outside terminations for obstruction and confirm the condensate drain is not visibly backed up. Anything inside the combustion path is technician work.

Limit, overheat and airflow faults

A limit fault means the furnace got hotter than it is allowed to get and the high limit switch opened to stop it. The furnace is not the problem in most of these calls. Airflow is.

Run the logic backward from the heat exchanger. Heat is being produced at a fixed rate; if not enough air is passing over the exchanger to carry it away, temperature rise climbs past the design range printed on the rating plate and the limit opens. So the technician chases airflow: filter condition and whether someone installed a filter far more restrictive than the system was designed for, closed or blocked supply registers, furniture or a rug over a return grille, a dirty blower wheel with caked buildup in the blades, blower speed set wrong for the installed configuration, a failing capacitor or motor, a collapsed flex duct in the crawlspace, or a plugged indoor coil sitting above the furnace from the cooling side of the system.

Repeated limit tripping is not something to live with. Cycling on the limit stresses the heat exchanger through hard thermal swings, and a cracked exchanger is a combustion safety issue, not just a repair bill.

Homeowner scope here is genuinely useful: replace the filter with the correct size and a reasonable restriction rating, open the registers, clear the returns. If the fault returns after that, stop and book a service call rather than resetting it repeatedly through the winter.

Control, wiring and communication faults

This group covers everything that is electrically wrong rather than mechanically wrong, and it is where the older housing stock across East Vancouver and New Westminster produces surprises.

Line-voltage issues come first. Many furnace controls are polarity sensitive and require a proper ground, because flame rectification depends on the ground path. A receptacle or junction wired with hot and neutral reversed, or a ground that was never properly bonded, will produce faults that look like sensing problems and drive people to replace perfectly good parts. A technician checks this early precisely because it is cheap to verify and expensive to miss.

Then low voltage. The transformer output, the fuse on the control board, thermostat wiring that a renovation nicked inside a wall, a shorted wire at the outdoor unit rubbing on a cabinet edge, corroded terminals in a damp crawlspace, or a common wire that was never pulled for a thermostat that needs one.

Communicating systems add their own vocabulary. Where the furnace, thermostat and outdoor unit exchange data over a bus, faults can describe a lost or garbled conversation rather than a failed component, and they require the manufacturer’s service literature to interpret properly.

Software-flavoured problems exist too: a board that needs its configuration set for the installed blower or staging, or a thermostat configured for the wrong equipment type. Those are diagnosis, not parts.

Safe resets, hard stops, and gas and CO safety

If you smell gas, or a carbon monoxide alarm sounds, do not troubleshoot. Get everyone out of the house, leave the door open behind you, do not flip switches or use anything electrical on the way out, and from outside the home call the gas utility’s emergency line and a licensed technician. That instruction is not boilerplate. It is the whole reason lockouts and safety switches exist.

A single reset after an obvious cause has been corrected is reasonable: you replaced a clogged filter, you cleared snow off the vent termination, the power blinked during a windstorm. Turn the furnace switch off, wait a minute, turn it back on, and watch what happens. Record the code again if it returns.

Repeated resets are not reasonable. If a furnace locks out twice on the same fault, something is failing and the control is refusing to run for a reason. Never jumper, bypass, or tape a switch closed to keep heat going, and be sceptical of any advice that suggests it. Pressure switches and limits are the last line between a combustion problem and your household.

When the code comes back, have your model and serial number, the exact flash pattern, and what you had already checked. Then call HeatLand at (604) 330-3812 for licensed, TSBC-certified diagnosis in Metro Vancouver and the Fraser Valley.

Quick Checklist

• Watch several full cycles and write down the exact flash pattern, including pauses
• Photograph the rating plate: model number, serial number, manufacture date
• Find the diagnostic label inside the furnace cabinet and use it over any online chart
• Do not cut power before recording the code, since it may clear stored fault history
• Check and replace the air filter with the correct size and a reasonable restriction rating
• Walk outside and confirm the vent and intake terminations are clear of snow, debris and nests
• Confirm the gas shutoff is open, the furnace switch is on and the thermostat is calling
• Stop after one reset; leave the home and call the gas utility and a technician if you smell gas or a CO alarm sounds

Frequently Asked Questions

Reviewed by the HeatLand Heating & Cooling team — licensed, insured, TSBC-certified HVAC contractor serving Metro Vancouver & the Fraser Valley since 1999. Error codes, specifications, pricing and rebate programs vary by model and change over time; confirm details against your unit’s own manual, a written quote, and the manufacturer or CleanBC/FortisBC. If you smell gas or your CO alarm sounds, leave the home and call the gas utility and a licensed technician from outside.