MAINTENANCE — Toronto, Etobicoke & GTA
Spark Plug Replacement
A worn spark plug rarely announces itself with a warning light first — rough idle, hesitation, and a quiet drop in fuel economy usually show up before that.
321 Rexdale Blvd #4, Etobicoke
Mon–Fri 8am–5pm · (416) 742-4521
Spark plugs ignite the fuel-air mixture in each cylinder, and a worn plug doesn't always announce itself with a warning light. Often it shows up first as a rougher idle, a slight hesitation off the line, or a small drop in fuel economy — subtle enough that most drivers chalk it up to "the car just feels a bit off" for weeks before the real symptoms appear.
Radman Auto Repair replaces spark plugs to the correct type, gap, and torque spec for your specific engine — not a generic one-size-fits-all part — using quality brands like NGK and Denso.
Signs Your Spark Plugs Need Replacing
Rough Idle or Engine Misfire
A worn or fouled plug can fail to ignite the mixture consistently, producing a shaky idle or an occasional misfire — often accompanied by a flashing or steady check engine light.
Hard Starting
Worn plugs need more voltage to fire reliably. On a cold morning or after the car has sat, that gap can be the difference between an instant start and several seconds of cranking.
Reduced Acceleration or Power
Incomplete combustion from a worn plug means less usable power reaching the wheels — often felt as sluggish response when merging or accelerating from a stop.
Lower Fuel Economy
Inefficient combustion burns more fuel to produce the same power, so a gradual drop in mileage over several tanks is a common early sign worth checking.
Plug Type Matters — Copper, Platinum & Iridium
Not all spark plugs are interchangeable, even within the same physical size. Copper plugs are the shortest-lived option, typically rated for 30,000–50,000 km. Platinum and iridium plugs use harder, more durable electrode materials and are commonly rated for 80,000–160,000 km depending on the manufacturer's specification for your engine. Installing the wrong plug type — or the correct type at the wrong gap — can cause misfires, poor fuel economy, or in some cases contribute to coil pack strain over time. We install to the exact type, gap, and torque spec your manufacturer calls for.
Important: a repeat misfire code after a plug replacement often points to a different underlying issue — a failing ignition coil, a fuel delivery problem, or a vacuum leak — rather than the plugs themselves. We diagnose before assuming a second set of plugs will fix a repeat code.
Frequently Asked Questions
How often should spark plugs be replaced?
Copper plugs typically need replacement every 30,000–50,000 km. Platinum and iridium plugs are commonly rated for 80,000–160,000 km, depending on your manufacturer's specification. We confirm the correct interval for your specific engine.
What happens if I keep driving on worn spark plugs?
Worn plugs cause less efficient combustion, which can lead to rough idle, misfires, reduced power, and lower fuel economy. Over time, repeated misfires can also put extra strain on the ignition coils and catalytic converter.
Can a worn spark plug cause a check engine light?
Yes. A misfire caused by a worn or fouled plug is one of the most common causes of a check engine light, often showing a P0300-series misfire code.
Do you use OEM-spec spark plugs?
Yes. We install plugs matched to your manufacturer's specified type, gap, and torque — using quality brands like NGK and Denso — rather than a generic universal-fit plug.
Etobicoke's Spark Plug & Ignition Specialists Since 1999
Radman Auto Repair has replaced spark plugs to manufacturer spec in Etobicoke since 1999 — diagnosing repeat misfires rather than assuming a second set of plugs is the fix.
Why Choose Radman
✓ Correct plug type, gap & torque for your engine
✓ Quality NGK & Denso parts
✓ Misfire diagnosis before assuming plugs alone
✓ Loaner vehicles available