The usual root causes are age, heat, oil in the spark plug wells, worn plugs that overwork the coils, or moisture in connectors. This reflects Jerry’s experience helping over 40,000 customers access accurate repair prices.
You’ll learn how to judge urgency, the likely causes, common repairs, and when to call a pro. We’ll also cover simple steps to prevent bigger damage and save money, whether you have coil-on-plug ignition or are dealing with coil pack failure. For quick ignition coil replacement cost estimates and nearby shops, you can use the Jerry app — no phone calls.
Real customers Jerry helped
Price points can vary based on unique factors, Jerry uses real customer experiences to reduce the guesswork and show what drivers are paying right now. Here are some examples:
Estimates are modeled based on real vehicle and location data; names have been changed. Actual prices will vary by shop, parts, and vehicle condition.
At-a-glance: Can I keep driving?
Before you decide to keep driving, match what you’re feeling with the list below. These buckets are helping Jerry customers avoid safety risks and prevent expensive damage.
- 🚨 Urgent — turn it off and get help now.
- Flashing Check Engine Light with shaking (misfire can damage the catalytic converter fast).
- Strong fuel smell, popping/backfire, or stalling in traffic (fire and safety risk).
- No-start or severe loss of power (you can’t maintain speed safely).
- Overheating from heavy misfire load (engine stress climbs quickly).
- 🕒 Soon — okay to drive, fix this week.
- Solid Check Engine Light, mild misfire under load.
- Rough idle that smooths out at speed.
- Poor fuel economy or sluggish acceleration.
- Misfire only on cold start but improves when warm.
- ✅ Monitor — safe to drive.
- Occasional stumble in rain or after a car wash.
- Brief hesitation on first start of the day with no warning lights.
These distinctions matter because misfires send raw fuel into the exhaust. That overheats and melts the catalytic converter first, which then can stress the engine and O2 sensors. Acting early turns a big bill into a smaller one.
Symptoms
Use the table to match your situation to a likely cause and a ballpark fix. Jerry is seeing prices vary by engine layout, parts quality, and access time, but the table gives a sense of ignition coil replacement cost.
Note: Some engines require intake manifold removal to reach rear coils (adds labor). Hybrids/EVs don’t use traditional coils for propulsion.
Risks if you ignore it
Before you put this off, consider the downsides, especially catalytic converter damage. Jerry customers find that small misfires can snowball into costly repairs.
Catalytic converter damage: Raw fuel overheats and melts the converter, turning a few hundred into four figures. If the converter glows red or you smell sulfur, stop.
Engine wear: Misfires cause shaking and uneven loads that stress mounts and internals.
Safety risk: Stalling or loss of power can leave you exposed in traffic.
Higher fuel spend: Incomplete burn wastes fuel and fouls plugs, raising costs.
Sensor damage: Prolonged misfire can poison O2 sensors, adding more parts to replace.
Most early fixes for coils and plugs land in the “hundreds, not thousands” if you act quickly.
Can I fix this myself? (DIY vs. pro)
Jerry customers start by staying safe and confirming the basics. Coils are high-voltage parts, but many are easy to reach on top of the engine. Safety protocols: park on level ground, engine cool (cold aluminum heads), key off, and avoid metal jewelry around battery and coils. Never unplug coils with the engine running.
DIY (easy, low risk):
- Battery/charging quick check: ~12.6V engine off; ~13.7 to 14.7V running. Low voltage stresses coils.
- Inspect coil connectors/wiring for looseness, corrosion, broken tabs, or cracked boots. Look for carbon tracking (black lightning-like lines) and oil in wells.
- Swap the suspect coil with a neighboring cylinder. If the misfire code moves, the coil/boot is the culprit; if not, consider injector/vacuum/compression.
- For wet-only misfires, lightly mist with water around boots at idle (then dry). Arcing indicates boot/coil issues.
- Replace accessible spark plugs if overdue. Verify correct plug type and gap; blow out debris before removal. Start new plugs by hand, then torque to manufacturer’s specifications.
- Apply a pea-sized dab of dielectric grease inside boots (not on electrodes).
- Tools: OBD-II scanner/app (with Mode $06), torque wrench, spark plug socket with magnet, feeler gauge, compressed air, small pick for brittle connectors.
Pro (recommended):
- Run full misfire diagnosis with live data/freeze-frame, Mode $06, and fuel trims to confirm coil failure vs. fuel/air/compression.
- Scope-test coil current and primary/secondary patterns to find weak coils under load.
- Replace coil(s) and matched spark plugs, torque to spec, and update ECM if a TSB applies. Expect a $120 to $200 diagnostic fee; ask for the scan report.
- Repair oil leaks into plug wells (valve cover/tube seals) to protect new coils.
- Check for wiring damage and fragile connectors; P035X often points to circuit issues.
- Verify catalytic converter health after severe misfire to avoid repeat failures; perform additional engine diagnostics if condition remains.
Special notes:
- Turbo and high-heat engines eat coils faster; use quality OE or OE-equivalent parts (e.g., Denso/NGK for many Asian makes; Bosch/Delphi/Hitachi/Eldor for Euro; Motorcraft/Delphi for Ford/GM).
- Some German and direct-injection engines need intake removal or adaptations; allow extra labor. Transverse V6 rear banks are often access-limited.
- Coil packs (not coil-on-plug) should be replaced as a unit to avoid repeat visits.
What NOT to do:
- Don’t keep driving with a flashing Check Engine Light. That indicates an engine misfire, which dumps unburned fuel into the exhaust and will cause catalyst damage.
- Don’t wash the engine bay or spray coils with cleaners. Moisture causes tracking and misfires.
- Don’t mix old, weak plugs with new coils on high-mileage engines. The imbalance shortens coil life.
- Be careful if you’re replacing spark plugs, especially with aluminum cylinder heads. Start the plug with hand pressure only, then tighten with a ratchet or wrench.
- Don’t over-torque spark plugs and coil bolts, as aluminum threads strip easily.
Before you book, use the Jerry app to compare quotes from shops near you and ask about brands, torque/spec adherence, and any TSBs that apply.
Prevention
Jerry customers are following a few simple habits to keep coils happy. Heat, moisture, and worn plugs are the main enemies.
Replace spark plugs on schedule for spark plug type and replacement intervals. Fresh plugs reduce coil strain.
Fix valve cover and plug tube seal leaks promptly. Oil in plug wells kills coils.
Keep battery and charging system healthy. Low voltage makes coils work harder.
Avoid pressure washing the engine. If water gets in, let coils dry fully before driving.
Use quality coils and plugs that meet OE specs. Cheap parts fail early under heat.
Periodically inspect connectors and boots for cracks; add dielectric grease during plug service.
After a misfire, clear codes and recheck soon. Catching repeat misfires early protects the catalytic converter.
Set maintenance reminders and check open recalls so you don’t miss plug intervals or important coil-related bulletins.
What our customers are asking
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How do I know if a coil is failing vs. a bad plug?
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Is a little roughness on cold start normal?
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Should I replace all coils or just the bad one?
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Why does it misfire only in rain or after a wash?
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Will a bad coil damage my catalytic converter?
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Are there recalls or TSBs for ignition coils?
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How much does a typical coil repair cost?
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Can an ECM or ignition module cause “coil-like” symptoms?
Steve Kaleff began working on cars at the very young age of nine years old, when his dad actually let him make fixes on the family car. Fast forward to the beginning of a professional career working at independent repair shops and then transitioning to new car dealerships. His experience was with Mercedes-Benz, where Steve was a technician for ten years, four of those years solving problems that no one could or wanted to fix. He moved up to shop foreman and then service manager for 15 years. There have been tremendous changes in automotive technology since Steve started his professional career, so here’s looking forward to an electric future!
Nick Wilson is an editor, writer, and instructor across various subjects. His past experience includes writing and editorial projects in technical, popular, and academic settings, and he has taught humanities courses to countless students in the college classroom. In his free time, he pursues academic research, works on his own writing projects, and enjoys the ordered chaos of life with his wife and kids.
