Part explained
Ignition coil replacement: price, symptoms and diagnosis
An ignition coil rarely fails on interval — it fails when it fails, usually one at a time. The symptom is typically clear: a sputtering engine, a flashing check engine light and a "misfire detected" fault code on a specific cylinder. This page explains how to pinpoint the failed coil, what a new one costs and when it's smarter to replace the whole set. Compare ignition coils from Dutch sellers without obligation.
By the onderdelen.autos editorial team · Updated · About the editorial team
What does the ignition coil do?
The ignition coil converts the 12 V onboard voltage into the 20,000 – 40,000 V required to make the spark plug arc over. On modern engines there is one coil per cylinder, mounted directly on top of the spark plug (coil-on-plug). Older engines use a single central coil with HT leads, or a twin coil that fires two cylinders at once. Wear is mostly in the internal windings, which slowly degrade under heat and vibration — often the first coil fails around 100,000 km and the rest follow within 30,000 km.
Signs of a failing ignition coil
- Check engine light on (steady amber) or flashing (red, severe — back off immediately).
- Sputtering or shaking at idle, as if the engine is running one cylinder short.
- Power loss and hesitation on acceleration, especially under load.
- Fault code P0301 to P0306 ("misfire detected, cylinder X") on the OBD-II reader.
- Rough running or misfires in wet weather — moisture shorts the coil to ground.
- Higher fuel consumption and a petrol smell from the exhaust (unburned fuel).
- In severe cases: engine stalls at idle or refuses to start.
When to replace
There is no fixed km interval for ignition coils — you replace on complaint, not on time. As a guide: the first failed coil shows up between 80,000 and 150,000 km depending on brand and driving conditions. Heat (turbocharged engines) and short trips accelerate it. Pinpoint the failed cylinder with an OBD-II reader — the code identifies the cylinder. Swap the suspect coil with a neighbouring cylinder; if the code moves with it, the coil is the culprit. On a car beyond 150,000 km with one failed coil it is wise to replace the whole set — the others are on the verge.
What does a new ignition coil cost?
A single coil costs around € 25 – € 60 aftermarket; OEM or premium (Bosch, Beru, NGK) between € 50 and € 150. Used from a Dutch dismantler: € 10 – € 50, but bear in mind a coil from a 150,000 km car has already used part of its life. Workshop cost: 0.5 – 1 hour labour, often combined with a fresh set of spark plugs since the coil cover is off anyway. For a full set of four coils the workshop usually doesn't charge four times the labour.
| Condition | From | To |
|---|---|---|
| New | € 25 | € 150 |
| Used / refurbished | € 10 | € 50 |
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DIY or workshop?
Difficulty: Medium
On coil-on-plug engines this is a half-hour job: release the connector, undo the bolt, pull the old coil straight up, fit the new one and reconnect in reverse. Important: pull the coil straight up (don't lever — the ceramic foot of the spark plug below cracks easily). On older engines with HT leads it's a little more work — swap the leads one at a time to avoid mixing up the firing order. After the swap always clear the fault code and test-drive a few kilometres.
- Socket set (usually 8 or 10 mm for the coil bolt)
- OBD-II reader to read and clear the misfire code
- A small screwdriver for the coil connector clip
- Anti-seize for the spark plug bore (no copper grease on the coil base)
Frequently asked questions
How do I tell if it's the coil or the spark plug?
Swap the coil from the reported cylinder with a neighbouring cylinder — does the misfire code move? Coil. Stays put? Spark plug or HT lead. This takes five minutes and saves an unnecessary purchase.
Should I replace all coils at once?
Not mandatory, but sensible beyond 150,000 km. The other coils share the same history; often the second and third failed coil follow within a year. Buying a set is cheaper than four separate purchases plus labour.
Is driving with a misfire harmful?
Yes. Unburned fuel reaches the catalytic converter and overheats it — a destroyed catalytic converter costs many times more than a coil. Flashing check engine light = back off immediately and repair as soon as possible.
Can I buy a used coil?
Yes, for a temporary fix or an older car. Ask the seller for mileage and a short warranty where possible (many Dutch dismantlers offer 3 months). For a car you plan to keep for years: new is cheaper in the long run.
Do I need to replace the spark plugs too?
Not automatically, but if the plugs are over 60,000 km old it's worth it — the coil cover is open anyway and it saves labour at the next service. Worn plugs are also a common cause of coil damage.
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Ignition coils in Dutch stock
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