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Spark Plug Cable Replacement
How Much does a Spark Plug Cable Replacement Cost?
Spark plugs ignite the air-fuel mixture in the combustion chamber, but the spark needs to come from somewhere.
Spark plug cables transfer the electrical charge from an ignition coil to your car’s spark plugs, and it is hard work.
All the heat and electricity they experience cause spark plug cables to wear out.
Manufacturers usually have recommended an interval for replacement, typically around 100,000 to 160,000km, although replacement may be due sooner in harsh operating conditions.
The cost to replace spark plug cables is relatively minor, costing approximately $150 to $350, although speciality and high-performance models may be more.
If ignored, a minor repair like spark plug cable replacement can cause annoying running concerns.
What is a Spark Plug Cable?
Your car’s ignition coil converts your battery’s 12V power into a high-voltage pulse, around 25,000 volts or so.
That high-voltage charge needs to be carried to the spark plug without loss due to resistance. That’s precisely what spark plug cables are designed to do.
The conducting cable is encased in a protective cover of silicone or rubber along with a thick layer of shielding material.
This prevents the high-voltage charge from arcing to a grounded location, sapping strength from the spark.
One end of each spark plug cable connects to an ignition coil while the other attaches to the spark plug.
There’s single spark plug cable for each spark plug. Over time, the insulation can degrade due to engine heat, or cracked spark plug cables can arc, and they will need to be replaced.
Symptoms that your Spark Plug Cables Require Replacing
- Check Engine light is illuminated due to misfire codes
- Your engine stumbles or runs rough
- The engine is hard to start
- The exhaust smells rich due to unburned fuel
- Black carbon tracking on spark plug cable ends where arcing occurs
- Noticeable damage to spark plug cables
How are Spark Plug Cables Replaced?
- The technician matches a new spark plug cable to the old one while still on the car
- The old spark plug cable is detached from the spark plug and the ignition coil using special spark plug cable pliers
- The new cable is fitted in the same orientation as the old part
- Any computer codes are cleared by the technician and the car is road tested to confirm the repair
Tips to Remember
- Spark plug cables should be replaced as a complete set whenever possible
- Many spark plug cable sets indicate the correct cylinder location on the wire itself to help ensure correct placement
- Replacing one cable at a time eliminates the risk of crossing wires and poor running conditions
How Important is Spark Plug Cable Replacement?
As routine maintenance, spark plug cable replacement ensures your car will run smoothly and trouble-free.
When there’s a concern such as a misfire, replacing your work or damaged spark plug cables can correct several concerns including excessive emissions, declining engine performance, and excessive fuel consumption.
If the cables are in extremely bad condition, your engine may be difficult to start or it may stall.
While it likely won’t contribute to a dangerous driving situation, it can provide peace of mind knowing your spark plug cables have been replaced.
If you’ve read this far, you obviously care about your car. A lot. So next time you need a service, repair or inspection, visit AutoGuru.com.au.
We let you search and book from over 1600 qualified mechanics, who eat car troubles for breakfast.
Image credit - David Baker
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