How the price estimate was built
What it shows: Our default range is $200 to $372; 3 of 4 published ranges overlap it.
What does this cost in your state?
California is the costliest state and Arkansas the cheapest; each square shows that state's midpoint of the estimate.
Lower-cost states ($249)MiddleHigher-cost states ($317)
What it shows: CA is the highest at $317 and AR the lowest at $249, across 51 states.
Counts below are complaints filed with NHTSA, not failure rates: a longer bar means more owners reported it.
Is your car affected?
What it shows: The most common band for complaints about this repair is 50,000-100,000 (53%). The biggest difference from all complaints is under 50,000: 18% against 60%.
What it shows: The most common band for complaints about this repair is 6-9 years (56%), against 23% for all complaints: the biggest difference between the two.
Is it urgent, and what do owners notice first?
2,782 owner complaints name this part.
What owners describe. Warning light: 60%; Stalled or lost power: 21%.
Use the owners' words ("warning light") when you describe the problem to a shop, and ask what test they ran.
Which trouble codes do owners report?
P0302 Cylinder 2 Misfire Detected leads at 57.
The code owners quote most is P0302. Read your own code from a scan and give the shop the exact code, not only "the light is on".
What do owners say it led to?
Among the 2,782 owner complaints naming this part, owners most often say engine damage followed.
What owners say happened after the problem. Engine damage: 129 (5%); Loss of power: 76 (3%); Stalled while driving: 12 (0%).
If your car shows the signs above, get it checked before it gets as far as engine damage.
Which other parts do owners name in the same complaint?
Among the 2,782 owner complaints naming this part, ignition coil is named in 23% of them, more than any other part.
Owners name the ignition coil most often in the same complaint, which is not proof that one caused the other. Ask the shop whether it checked the ignition coil too, so you are not quoted twice for one visit.
What did owners say they paid?
Half of the 74 owners who wrote a dollar amount gave $1,000 or less; one in ten wrote more than $5,076.
These are bills owners wrote down, often covering more than this one repair. They show how far a job can run; get written quotes for your own car.
How fast were owners driving when it happened?
55 mph or faster leads at 43%.
Owners reported it most often at highway speed. Tell the shop what speed it happens at, because that narrows the diagnosis.
How serious did it get for owners?
Among the 2,782 owner complaints naming this part, being towed is the outcome owners report most often.
What it shows: Towed is the largest at 139, followed by Fire reported at 16; the smallest shown is Injury reported at 8.
Which model years show up most in the complaints?
Among the 2,782 owner complaints naming this part that state a model year, complaints cluster in a few model years instead of spreading evenly.
What it shows: 2017 is the largest at 775 (28%), followed by 2015 at 257 (9%); the smallest shown is 2025 at 13 (0%).
Is this repair covered by an emissions warranty?
Federal rules require carmakers to cover the catalytic converter, the emissions computer and the onboard diagnostic system for 8 years or 80,000 miles, and any part whose failure fails an emissions test for 2 years or 24,000 miles; California requires 3 years or 50,000 miles on every emission part.
| Warranty | Covers | Length |
|---|---|---|
| California, all emission parts | All emissions-related parts | 3 years or 50,000 miles |
| California, high-cost parts | Specific high-cost emission parts listed in the owner manual | 7 years or 70,000 miles |
| Federal, basic | Any part that causes an emissions failure | 2 years or 24,000 miles |
| Federal, extended | Catalytic converters, electronic emissions control unit (ECU), onboard emissions diagnostic device or computer (OBD) | 8 years or 80,000 miles |
Which engine sizes show up most in complaints about this part?
Among 2,750 owner complaints about this part where the VIN identifies the vehicle, 26% involve engines of under 1.6 L, against 11% of complaints about all the parts we track.
What it shows: 1.6 to 2.0 L is the largest at 37%, followed by under 1.6 L at 26%; the smallest shown is over 5.0 L at 4%.
What do emissions repairs cost?
Among 46,033 California vehicles repaired to pass a Smog Check in 2025, 39.1% cost over $650 to fix and the average bill was $757.
What it shows: Over $650 is the largest at 39.1%, followed by $1 to $100 at 13.1%; the smallest shown is $501 to $650 at 8.4%.
Do spark plug replacement problems track gallons of motor gasoline burned per resident per year across states?
A weak hint, not a firm finding: across U.S. states, NHTSA owner complaints about spark plug replacement run higher where gallons of motor gasoline burned per resident per year is higher, after adjusting for the makes sold in each state. This is an association across states, not proof that gallons of motor gasoline burned per resident per year causes this repair.
How to read it: Each dot is a state. Further right means more gallons of motor gasoline burned per resident per year (seds, transportation); higher up means more complaints for this repair than expected (1.0 is average). If the dots climb to the right, reports of this repair rise with gallons of motor gasoline burned per resident per year (seds, transportation).
What it shows: States with more gallons of motor gasoline burned per resident per year (seds, transportation) tend to sit higher on the chart across 41 states: a pattern in the data, not proof of cause.
- The 10 states with the most gallons of motor gasoline burned per resident per year (Alabama, Mississippi, South Carolina, Missouri, New Hampshire, Arkansas, Kentucky, Tennessee, Texas, Delaware): reports of this repair run 5% above what the makes sold there would predict, and 7 of 10 are above expected. The 10 with the least (New York, California, Washington, Illinois, Oregon, Rhode Island, Pennsylvania, Massachusetts, Nevada, Maryland): 3% below, and 3 of 10 are above expected.
- Exceptions: South Carolina, New Hampshire and Texas are among the highest in gallons of motor gasoline burned per resident per year but report below expected; Rhode Island (83% above expected) is among the lowest but above expected.
- Split the states into thirds: the third with the least gallons of motor gasoline burned per resident per year runs 5% below what the makes sold there would predict, the middle third 7% above, and the third with the most 9% above. Most of the gallons of motor gasoline burned per resident per year effect sits between the lowest and the middle third.
- For gallons of motor gasoline burned per resident per year, after allowing for the 1562 comparisons we ran, luck alone would produce a pattern this strong about 1 time in 5. The gallons of motor gasoline burned per resident per year pattern leans on New York: without it, it weakens.
- Weak spot: compare only states with similar workers who drive alone to work and the pattern keeps about 0% of its strength, so part of it may come from workers who drive alone to work instead of gallons of motor gasoline burned per resident per year.
- For gallons of motor gasoline burned per resident per year, of the 5 exception states, 2 read the same way for the other parts of the system (so that is the system there, not this repair) and 3 are specific to this repair.
Where residents burn more gasoline they drive more miles, and brakes, tires, belts and suspension wear out with miles.
Are the parts for this repair getting more expensive, or only the labor?
The federal producer price index for new spark plugs and other complete engine electrical equipment rose 33.5% from December 2019 to August 2026, while the consumer price index for motor vehicle repair, labor and parts together, rose 55.2% (BLS, national).
What it shows: New electrical and electronic engine equipment parts is the largest at +57.0%; the smallest shown is All motor vehicle parts at +17.4%.
Has this part been recalled abroad on cars that may share it?
Manufacturers filed 1 foreign recall campaigns that name spark plug with NHTSA since 2015 (matched by the filing text); the latest, from Toyota Motor Corporation in 2022-01.
| Filed | Manufacturer | Foreign recall no. | What the filing says |
|---|---|---|---|
| 2022-01 | Toyota Motor Corporation | 003 | Description of Problem: The subject vehicles are equipped with a 9NR engine containing ignition coils, which are used to raise the voltage of the electricity from the vehicle battery to ignite the spark plugs. |
If this part was recalled, is the repair free?
Federal law (49 U.S.C. 30120) requires a maker to fix a recalled defect without charge for cars first bought within 15 calendar years (tires within 5), and NHTSA lists 1 recall campaigns for parts matched to a spark plug replacement since model year 2015, covering about 7 vehicles.
| Rule or count | What it says |
|---|---|
| Age limits | The free-remedy duty does not apply to a car first bought more than 15 calendar years, or a tire first bought more than 5 calendar years, before the recall notice. |
| Failure to fix | A repair not done adequately within 60 days of presentation is prima facie evidence of failure to repair within a reasonable time; the maker must then replace the vehicle or refund the purchase price less depreciation. |
| Free remedy | A maker must fix a recall defect without charge. |
| NHTSA recalls matched to a spark plug replacement since model year 2015 | 1 recall campaigns covering about 7 vehicles |
Does my engine design make this repair more likely?
EPA's Automotive Trends data show turbocharged gasoline engines in 44.4% of new gasoline cars in model year 2024 against 1.4% in 2005, and turbo engines run hotter and wear spark plugs and coils sooner (sales-weighted national shares).
| Model year | Turbocharged | Direct fuel injection | Average cylinders | Average horsepower |
|---|---|---|---|---|
| 2000 | 1.2% | 0.0% | 5.7 | 181 |
| 2005 | 1.4% | 0.0% | 5.8 | 209 |
| 2010 | 2.6% | 8.3% | 5.3 | 214 |
| 2014 | 13.8% | 37.8% | 5.1 | 231 |
| 2018 | 29.6% | 60.5% | 5.0 | 239 |
| 2021 | 31.8% | 72.1% | 5.0 | 251 |
| 2024 | 44.4% | 79.5% | 4.7 | 247 |
Is it recalled or covered?
| Recall number | Vehicles | Cars recalled | What the recall says |
|---|---|---|---|
| 21V-124 | Mercedes-Benz AMG CLA45 2020 | 7 | Engine damage may result in an engine stall, increasing the risk of a crash. |
A bulletin is a repair procedure a maker sends its dealers, not a safety defect: if your maker is listed, ask the dealer whether one covers your car and quote its number.
| Maker | Vehicles | Bulletin number | Date | What it says |
|---|---|---|---|---|
| Jeep | Grand Cherokee L 2026–2027; Grand Cherokee 2026–2027 | 66D Combo Rev1 | Jul 27, 2026 | Customer satisfaction notification north america Spark Plugs Reference: 66D The spark plugs insulator on approximately 48,000 of the above vehicles may break due to excessive cylinder pressure. |
| Jeep | Grand Cherokee 4xe 2026; Grand Cherokee 2026 and 1 more | 66D Dealer | Jul 22, 2026 | Spark Plugs The spark plugs insulator on approximately 48,000 of the above vehicles may break due to excessive cylinder pressure. |
| Jeep | Grand Cherokee L 2026; Grand Cherokee 2026 | 112536 | May 27, 2026 | Claim submission for hurricane spark plug. |
| Jeep | Renegade 2022–2025; Compass 2022–2025 | 09-026-25 | Sep 3, 2025 | Not applicable to vehicles built for US market. |
| Land Rover | Range Rover 2023–2025; Range Rover Sport 2023–2025 | SFCC_FEB2025_47 | Feb 14, 2025 | MIL on, misfire , or fuel smell after spark plug service. |
| Dodge | Challenger 2023 | 09-016-24 | Jul 17, 2024 | Spark Plug Re-Gap to Resolve Misfire Symptoms Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): P0300 - Multiple Cylinder Misfire. |
23 more bulletins name this part; the car finder at the top checks yours, and the NHTSA bulletin file linked below lists them all.
What do owners say?
4 complaints quoted word for word, each with its NHTSA number.
That statement couldn't be more INACCURATE a few weeks ago I was told I needed a new head/spark plugs and the block was warp and I would not be able to drive it until it was repaired (a $5k job).
Another $980 a couple weeks ago for battery , spark plugs , computer software update etc.
About $1,000 was spent on "cleaning" the engine and replacing the spark plugs and other effected components, with no improvement on oil consumption.
My car is currently at dealers getting looked at and they recommended changing my fuel injector and spark plugs, which they completed ($2,000) and I AM STILL having issues.!!!
Check your car
Our calculator's default spark plug replacement cost is $200–$372 for four iridium plugs, parts plus labor at $120 an hour. Plug type, how many cylinders your engine has and the shop you choose move that number.
What does the spark plug price cover?
The estimate covers one plug per cylinder and the labor to swap them, at the hourly rate for the shop type you pick. It does not cover anything the job uncovers: a cracked coil boot, a seized plug that has to be extracted, or a leaking valve cover gasket that is oil-fouling the plugs.
Taxes, shop fees and a diagnostic charge are also outside the range. Some shops waive the diagnostic fee if you approve the repair, so ask.
How much do plug type, cylinders and shop change the price?
Plug type is the biggest lever after cylinder count. Here are the calculator's ranges, changing one setting at a time from the default.
| Setting | Estimate |
|---|---|
| Default: 4 iridium plugs, $120/hr | $200–$372 |
| 3 cylinders | $178–$317 |
| Copper plugs (every 30k miles) | $136–$208 |
| Platinum plugs (every 60k miles) | $160–$272 |
| Independent shop (about $100/hr) | $182–$347 |
| Dealership (about $175/hr) | $252–$441 |
Copper is cheapest now but is replaced twice as often as platinum, so the lower price is not always the lower cost. Use the plug type in your owner's manual; a different type than the engine was built for is not a saving.
How do I know it is the spark plugs, and how urgent is it?
Worn plugs usually show up as a rough idle, hesitation when you accelerate, harder starting or a drop in fuel economy. A flashing check engine light with a shaking engine points to a misfire, and plugs are one of the usual causes along with ignition coils.
A misfire is not a reason to keep driving for weeks. Unburned fuel can overheat the catalytic converter, which costs far more than plugs. If the light is flashing, get it read this week. If the car only runs a little rough and you are near the interval in your manual, plan the job rather than rushing it.
How do I get a fair quote?
Give two or three shops the same details: year, make, model, engine size and the plug type your manual lists. Ask for the plug brand, the labor hours and any fees on separate lines. Compare quotes for the same plug type, because an iridium quote and a copper quote are not the same job.
For an outside check, RepairPal publishes $288–$399 for spark plug replacement. Ask the shop to show you the old plugs when you pick the car up.
What does the estimate leave out?
It is a range for a typical engine, not a quote for yours. Engines where the plugs sit under an intake manifold or behind other parts take more labor than a four-cylinder with plugs on top. Larger engines with more cylinders cost more than the default.
If a quote lands well above the range for your plug type and shop, ask what is being added before you pay. The next step is to enter your setup in the calculator and take that range with you.
Frequently asked questions
Can I replace spark plugs myself?
Many owners do on easy-access engines, and it saves the labor line. Gap and torque matter, and a cross-threaded plug can ruin a cylinder head, so skip it if the plugs are buried.
Should I replace the ignition coils at the same time?
Only if a coil is actually failing. Ask the shop to test them rather than replacing them by default.
Does the dealership always cost more?
Its hourly rate is higher, so the total is higher, but plug type moves the price about as much as shop type does.
Sources
Data shown on this page
- NHTSA owner complaint file (2015-2019 · 2020-2024 · 2025-2026) file downloaded 2026-10-05
- NHTSA recall file file downloaded 2026-10-05
- NHTSA service bulletin file (2015-2019 · 2020-2024 · 2025-2026) file downloaded 2026-10-05
- CalcScrape calculator model scaled by BEA Regional Price Parities data from 2024
- U.S. Code of Federal Regulations, 40 CFR 85.2103, and the California Air Resources Board warranty fact sheet file downloaded 2026-10-05
- NHTSA owner complaint files with VINs decoded by NHTSA vPIC data from 2025
- California Bureau of Automotive Repair, Smog Check Executive Summary Report 2025 data from 2025
- EIA State Energy Data System, motor gasoline consumption, joined to NHTSA owner complaints file downloaded 2026-10-06
- BLS Producer Price Index, commodity data for motor vehicle parts (series WPU1412051426); BLS Consumer Price Index item SETD for the repair row file downloaded August 2026
- NHTSA Office of Defects Investigation, Foreign Campaigns (filings under 49 CFR 579.11, public API) file downloaded 2026-10-05
- 49 U.S.C. 30120 (Remedies for defects and noncompliance), text via Cornell Legal Information Institute; NHTSA recall campaigns data from 2026
- U.S. EPA, The 2025 EPA Automotive Trends Report (EPA-420-R-26-001) file downloaded 2026-10
Terms: US government data, public domain.
Observed: records as filed; owner reports are unverified and are not failure rates. Modeled: our estimate, not a quote. Rule: a published legal rule, not a measurement; whether it covers a given repair depends on the car and the facts. Derived: computed from the records; an association, not a cause.
What is our own estimate
The price range comes from our calculator's formula. Its parts prices, labor hours per job and shop-rate tiers are CalcScrape estimates, not a published price dataset. Checked against 4 established price guides on 2026-10-04: our default's midpoint is 17% below the middle of RepairPal's range ($288–$399). Methodology