Blog · Guelph
What Actually Fails an Ontario Safety Inspection (and What It Costs to Fix)
Most cars don't fail a safety on anything dramatic. They fail on the same five things, and four of them are cheap.
Last updated September 4, 2026 · Reviewed by the Guelph Mechanic team
The five usual suspects
1. Brakes. Pads or rotors under minimum thickness, a seized caliper, or a parking brake that doesn't hold. This is the most common fail and the most expensive of the routine ones: $350–$700 an axle for pads and rotors.
2. Tires. Tread under the minimum, cords showing, sidewall damage, or mismatched sizes on an axle. Two tires installed run $250–$500 depending on size.
3. Lights. A single dead bulb fails the inspection. Cheapest fix on the list — often under $30 — and the one sellers should check before the appointment.
4. Exhaust. Leaks and loose or missing components. A muffler or a flex pipe is $200–$500.
5. Rust. Structural rust on rockers, frame rails or subframes, or holes in the floor. This is the one that can end a sale — repair costs range from a few hundred dollars for a patch to 'not worth it'.
The rest
Windshield cracks in the wiper sweep, worn wipers, a horn that doesn't work, seatbelts that don't retract, ball joints and tie rods with play, leaking shocks. All are fail items; most are modest repairs.
Avoiding two inspections
You pay for the inspection whether it passes or fails ($190 plus HST here), so the way to spend the least is to catch the cheap stuff first. Have the obvious stuff — bulbs, wipers, tire tread, a loud exhaust — checked before you book. If you're the buyer, get the safety and a pre-purchase inspection done together so you find out about the timing belt and the oil leak at the same visit.
What a pass doesn't mean
Ontario is explicit: the certificate is not a warranty. It says the car met the minimum standard on the day. It is silent on the transmission, the A/C, the engine's oil consumption and the rust that hasn't gone through yet.