Spark Plug Replacement
Spark plugs ignite the fuel mixture in every petrol cylinder, and the gap between the electrodes widens with each spark. Once it is too wide, the spark weakens and the engine misfires. Fresh plugs of the right type restore starting, smooth idle and economy.
From AED 399Written quote after diagnosis, before work startsConvenience fee applicable · shown on your written quote
- 1-2 hours for most four-cylinder engines; V6 and V8 take longer
- Pickup and delivery from your door
- Convenience fee applicable · shown on your written quote
- Diagnosis free with repair
Signs you need spark plug replacement
- Engine shudders at idle or when accelerating
- Long crank or hesitation starting from cold
- Misfire code or flashing check engine light
- Noticeably worse fuel economy
- Lack of power when overtaking
- Service interval reached, usually 30,000 to 100,000 km depending on plug type
- Engine feels flat on the highway even though it seemed fine in town
What usually causes it
Normal electrode wear
Every spark erodes the electrode slightly. Copper plugs wear fastest, while iridium and platinum plugs last longer but still widen over time.
Oil or fuel fouling
A plug coated in black soot suggests a rich mixture, while an oily one points to worn valve seals or rings. Reading the old plug tells us about the engine.
Wrong heat range or gap
Plugs that run too cold foul, those too hot cause pre-ignition. Turbocharged engines are especially sensitive to the correct gap.
Failing ignition coil
A weak coil produces a poor spark that fouls or damages a new plug. We test coils at the same visit so the new plugs are not wasted.
How we do spark plug replacement
- 1
Check the specification
We confirm the plug part number and gap for your exact engine, since the same model can use different plugs depending on year and turbo or naturally aspirated.
- 2
Remove coils and clean the wells
Coil packs come off and the plug wells are blown clean so grit does not fall into the cylinder when the plug is removed.
- 3
Inspect the old plugs
Colour and deposits show mixture, oil burning, overheating or ignition faults. We note what we find and tell you if it needs further work.
- 4
Fit and torque
New plugs go in by hand first to avoid cross-threading, then are torqued to the specification. Coils are checked, refitted and the engine is tested for misfire counts.
In Dubai, Sharjah and Ajman
Long periods of idling in traffic and high under-bonnet temperatures stress plugs and coils, so replacement at the shorter end of the manufacturer's interval is sensible for Dubai driving. Plugs removed from hot aluminium heads can seize, which is why we work on a cooled engine.
Questions about spark plug replacement
How often should plugs be changed?
Follow your owner's manual: roughly 30,000 km for copper, and between 60,000 and 100,000 km for iridium or platinum types. Turbo engines and heavy traffic favour the short end.
Should I change all plugs together?
Yes. They wear at similar rates, and changing all of them keeps the spark even across cylinders. Replacing one leaves worn plugs to cause the next misfire.
Can I use any brand of plug?
Use the specified heat range and type. The quote lists OEM and aftermarket plugs of the right specification, so you pick on price without compromising on fit. Used plugs are not offered, since a worn plug defeats the purpose.
Why do some plugs break or seize when removed?
Plugs left in a hot aluminium head for years can bond to the threads. We loosen them gradually with penetrating oil on a cool engine, and tell you before proceeding if a plug looks likely to damage the thread.
Will new plugs fix a misfire?
Often yes, but not always. If the cause is a coil, injector or compression, the misfire stays. We test the other ignition parts and measure the misfire counts after.
Last updated
Get a written quote
Tell us about your car. You get an itemised quote before any work starts, and you choose OEM, aftermarket or used parts.