P0303: Cylinder 3 Misfire Detected
Key takeaways
- P0303 means the engine computer saw cylinder 3 fire weakly or not at all, from tiny changes in crankshaft speed.
- A flashing check engine light means the misfire is bad enough to damage the catalytic converter: stop driving and get it checked.
- An ignition coil ($120–$300) or spark plugs ($150–$350 for a 4-cylinder set, $250–$600 on a V6 or V8) fix most cylinder 3 misfires at a US independent shop.
- Swapping the cylinder 3 coil with a neighbor and seeing whether the code moves is the cheapest test there is.
- Low compression from a valve or head gasket problem is the expensive outlier at $1,500–$4,500, which is why a compression test comes before big repairs.
What P0303 means
Cylinder 3 isn’t burning its fuel properly. Scanners call it “Cylinder 3 Misfire Detected.” Each time a cylinder fires, it gives the crankshaft a small push. The engine computer watches crankshaft speed through the crank sensor, and when cylinder 3’s push is missing or weak often enough, it sets P0303. The code tells you where the problem is, not what it is: spark, fuel, air or compression.
Is it safe to drive?
Short trips only, and only if the check engine light is steady. The car will usually shake at idle, feel down on power, and may hesitate under load.
The symptom that changes the answer is a flashing check engine light. Flashing means the misfire is bad enough that unburned fuel is heading into the catalytic converter, where it can overheat and destroy it. Pull over when it’s safe, and have it towed or driven the shortest possible distance. See check engine light flashing for what to do right now.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Failed ignition coil on cylinder 3 | Swap it with cylinder 2 or 4, clear codes; if the misfire moves, it’s the coil | $120–$300 per coil |
| Worn or fouled spark plug | Pull the plug and look for wear, oil, cracks or a wide gap | $150–$350 a set (4-cyl), $250–$600 (V6/V8) |
| Coil boot, plug wire or connector | Look for carbon tracking, cracks or oil in the plug well | $50–$200 |
| Clogged or leaking fuel injector | Swap test or injector balance test; misfire at idle more than under load | $250–$600 per injector |
| Vacuum leak near cylinder 3 | Smoke test the intake; lean codes alongside | $50–$400 |
| Low compression (valve, rings, head gasket) | Compression and leak-down test on cylinder 3; coolant loss can point to the head gasket | $1,500–$4,500 |
What to check first
- Check whether the light is steady or flashing. Flashing means stop.
- Pull the coil and plug on cylinder 3. Look for oil in the plug well, a cracked boot or a worn plug.
- Swap the cylinder 3 coil with a neighboring one, clear the code and drive. If it becomes P0302 or P0304, replace the coil.
- Swap the plug the same way if the coil didn’t move the misfire.
- Test the injector and compression before anything expensive, and check for coolant loss.
Clearing the code and driving is part of the swap test, not a fix on its own; a misfire that isn’t fixed comes back.
The bulletins show two patterns. Ford has bulletins for misfires on its 1.5L, 2.0L and 2.3L EcoBoost engines (2023–2025 Escape, Corsair, Nautilus, Explorer, Mustang), and Chrysler-group makes (Jeep, Ram, Dodge) have PCM software updates that list P0303 among other codes. In the NHTSA complaint data the Ford Escape leads with 65 owner reports, mostly 2017 and 2018 models.
What it costs
The cheap outcome is a coil, $120–$300, or a boot. The common outcome is a coil plus a set of plugs, about $150–$350 for the plugs on a four-cylinder and more on a V6 where the intake must come off. The expensive outcome is a compression problem at $1,500–$4,500, or a catalytic converter at $1,000–$2,500 if the car was driven with a flashing light. A $100–$180 diagnosis with a swap test and a compression check is how you avoid paying for the wrong one.
Related codes
P0303 often comes with P0300 (random misfire) and sometimes other single-cylinder codes like P0301. P0353 is the cylinder 3 coil circuit code; together with P0303 it points straight at the coil or its wiring. If the misfire went on long enough, P0420 can follow as the converter degrades. For a car that shakes with the light on, see check engine light and car shaking.
What owners report to NHTSA
378 complaints filed with NHTSA mention P0303, 355 of them since 2015, across 87 different models. The component owners most often filed it under: engine.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| FORD ESCAPE | 65 | 2006, 2014, 2017, 2018, 2019 |
| FORD EDGE | 34 | 2016, 2017, 2018 |
| CHRYSLER PACIFICA | 30 | 2017, 2018, 2019, 2020 |
| FORD FUSION | 22 | 2013, 2015, 2016, 2017, 2018 |
| HONDA CR-V | 21 | 2000, 2017, 2018, 2022 |
| HONDA ACCORD | 19 | 2000, 2008, 2010, 2018, 2019 |
| HONDA ODYSSEY | 16 | 2009, 2013, 2014, 2016, 2018 |
| KIA SOUL | 14 | 2012, 2014, 2016, 2018, 2021 |
| KIA SORENTO | 8 | 2014, 2016, 2018, 2021, 2022 |
| HYUNDAI TUCSON | 8 | 2017, 2018, 2019, 2022, 2023 |
Manufacturer service bulletins that name P0303
406 technical service bulletins and manufacturer communications filed with NHTSA mention P0303, from 29 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- ACURA ACURA (2021, 2022, 2023, 2019), bulletin 10233209: Service Bulletin - Under certain circumstances, the vehicle may experience driveability concerns. This may result in the following DTCs to set: P0300 (Random Misfire Detected), P0301 (No. 1 Cylinder Misfire Detected), P0…
- RAM 1500 (2025), bulletin 11008018: "Flash: Powertrain Control Module (PCM) Updates 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): P01…
- LINCOLN NAUTILUS (2024, 2025, 2023), bulletin 11010920: Some 2023-2025 Escape/Corsair vehicles equipped with a 1.5L or 2.0L EcoBoost engine, 2024 Mustang vehicles equipped with a 2.3L EcoBoost engine, 2024-2025 Nautilus, and 2025 Explorer vehicles equipped with a 2.3L EcoBoos…
- FORD EXPLORER (2025, 2023, 2024), bulletin 11010920: Some 2023-2025 Escape/Corsair vehicles equipped with a 1.5L or 2.0L EcoBoost engine, 2024 Mustang vehicles equipped with a 2.3L EcoBoost engine, 2024-2025 Nautilus, and 2025 Explorer vehicles equipped with a 2.3L EcoBoos…
- FORD MUSTANG (2024, 2023), bulletin 10253555: Some 2023-2024 Escape/Corsair vehicles equipped with a 1.5L or 2.0L EcoBoost engine, 2024 Mustang vehicles equipped with a 2.3L EcoBoost engine, and 2024 Nautilus vehicles may exhibit an engine misfire condition with dia…
- LINCOLN CORSAIR (2023, 2024), bulletin 10253555: Some 2023-2024 Escape/Corsair vehicles equipped with a 1.5L or 2.0L EcoBoost engine, 2024 Mustang vehicles equipped with a 2.3L EcoBoost engine, and 2024 Nautilus vehicles may exhibit an engine misfire condition with dia…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Can I drive with a P0303 code?
If the light is steady and the car runs close to normal, short trips to get it fixed are usually OK. If the light is flashing or the car shakes hard, stop: unburned fuel from the dead cylinder can overheat and ruin the catalytic converter.
Is P0303 always the spark plug or coil?
Most of the time, but not always. If a coil swap and new plug don't move or fix the misfire, the next suspects are the injector on cylinder 3, a vacuum leak near that cylinder, and low compression.
How do I find which coil is cylinder 3?
Cylinder numbering varies by engine; your owner's manual or a service manual shows it. On many inline four-cylinders cylinder 1 is at the timing-belt or chain end, but check before you swap anything.
Can a bad coil on cylinder 3 cause P0300 too?
Yes. A weak coil can make the computer log a random misfire (P0300) alongside P0303, especially under load. Fix the cylinder 3 fault first and see if both clear.