Whether you’re heading down the 401, navigating slushy backroads in Quebec, or cruising the Sea-to-Sky Highway, your vehicle’s check engine light means the same thing: your car’s talking—and it wants you to listen. But not all dashboard warnings are urgent, and some fault codes are more like friendly reminders than flashing red alerts.
This guide will break down what fault codes are, the different types you might encounter, and when Canadian drivers should take action—or take it easy.
What Are Fault Codes?
Today’s cars and trucks come equipped with onboard diagnostic systems (OBD-II for vehicles built since 1996). These systems monitor the engine, emissions, and other vital components, generating a diagnostic trouble code (DTC) when something goes wrong.
In colder climates like much of Canada, these codes can be triggered by more than just mechanical issues—extreme temperature swings, icy conditions, or even road salt buildup can occasionally throw sensors off.
The codes can be read by a scanner at a mechanic—or, more conveniently, by a mobile inspection service that comes to you, even in your own driveway.
The Main Types of Fault Codes (and What They Mean)
1. Stored (Active) Codes
-
What they are: These codes signal a problem that’s currently happening.
-
Typical Canadian example: An oxygen sensor fails during a -30°C cold start in Saskatchewan.
-
What to do: Don’t ignore these. If your check engine light is on and you have stored codes, book an inspection right away.
2. Pending Codes
-
What they are: The system spotted something off, but it hasn’t happened consistently enough to set off a full warning.
-
Typical example: A misfire caused by wet spark plugs after driving through a deep slush puddle.
-
What to do: Keep an eye on it. These may clear on their own, but if they return, have it checked.
3. Permanent Codes
-
What they are: These codes stay locked in until the vehicle’s computer confirms the issue has been fully resolved—not just cleared with a scanner.
-
Typical example: A failing catalytic converter that doesn’t pass emission-readiness tests in Ontario or B.C.
-
What to do: Yes, worry. Especially if you’re preparing for emissions testing or resale—these won’t go away until they’re truly fixed.
4. Historic (History) Codes
-
What they are: A record of past issues that no longer seem to be active.
-
Typical example: A one-time transmission hiccup during a snowy hill climb in Halifax.
-
What to do: Not a big deal unless it repeats. If the same historic code keeps coming back, it could be the sign of a deeper issue.
Why This Matters in Canada
-
Winter is tough on vehicles. Sub-zero starts, salted roads, and icy sensors can all cause temporary or false fault codes.
-
Used cars are hot in Canada. With high new car prices and long waitlists, Canadians are turning to used vehicles—and fault codes are key to knowing what you’re really buying.
-
Emissions inspections vary by province. Ontario and B.C., for example, have specific rules around vehicle emissions. Permanent codes tied to the emissions system could prevent a car from passing required testing.
When Should Canadian Drivers Be Concerned?
| Code Type | Should You Worry? | Action |
|---|---|---|
| Stored (Active) | Definitely | Book a diagnostic or mobile inspection |
| Pending | Maybe | Monitor and recheck if they return |
| Permanent | Yes | Repair the root issue before clearing |
| Historic | Only if repeated | Track patterns, especially in cold snaps |
Pro Tip: Inspect Before You Buy
Shopping for a used car? Many Canadian buyers don’t realize that sellers can clear stored codes to hide problems temporarily. But permanent or recently triggered fault codes still tell the truth. That’s why a mobile pre-purchase inspection is one of the smartest moves you can make—especially during the winter buying season when problems are harder to spot.
Need peace of mind before buying a used vehicle in Canada?
Book a mobile inspection with iNeedaPPi and get a full diagnostic and inspection report—without stepping foot outside.
