P0302 Code Explained (Cylinder 2 Misfire)
P0302 is one of the most common misfire codes beginners see when the engine is shaking, stumbling, or running rough. It means the misfire is happening in cylinder 2, not randomly across multiple cylinders.
Does your car shake at idle or vibrate when stopped? If the engine vibrates at stoplights or while idling, see Car Shakes When Idling →
P0302 means: Cylinder 2 Misfire Detected.
👉 In simple terms: cylinder 2 is not firing the way it should.
- If the engine is shaking or the light is flashing, avoid driving
- Check the spark plug and ignition coil on cylinder 2
- Swap the coil with another cylinder to see if the misfire moves
- Clear the code and see if it returns
In simple terms, your car’s computer has detected that cylinder 2 is misfiring. That means combustion in that cylinder is not happening correctly every time, which can make the engine run rough and can trigger the check engine light.
If you are brand new to scanning codes, learn how to use an OBD2 scanner step-by-step . If your check engine light just came on and you have not read the basics yet, start here: What Does the Check Engine Light Mean?
Quick tip: If the engine is shaking, the light is flashing, or the car feels weak, do not ignore a P0302 code. A single-cylinder misfire can still damage the catalytic converter if it continues.
Why You Got a P0302 Code (Simple Explanation)
Your engine is supposed to fire each cylinder in a smooth, repeating pattern.
If the computer detects that cylinder 2 is not burning the air-fuel mixture correctly, it can store a P0302 code.
In simple terms: cylinder 2 is missing combustion events when it should be firing normally.
Common Symptoms of a P0302 Code
When the P0302 code appears, the engine may feel rough, unstable, or weaker than normal. Sometimes the symptoms are very obvious, and sometimes they show up mostly during acceleration.
- Check engine light stays on or flashes
- Rough idle
- Engine shaking or stumbling
- Jerking during acceleration
- Loss of power
- Hard starting in some cases
- Reduced fuel economy
What This Code Feels Like (Real Situations)
P0302 can feel different depending on how severe the misfire is. Here are the most common real-world situations:
- Shaking at idle: The engine may vibrate more than normal at stoplights or while parked.
- Jerking when accelerating: The car may stumble or hesitate when you press the gas. See what hesitation during acceleration usually means →
- Flashing check engine light: This is a more urgent sign that the misfire is active right now.
- Mostly normal driving with a solid light: In some early cases, the car still feels somewhat normal, but the code is still important and should not be ignored.
If your main symptom is weak acceleration with the check engine light on, see this guide for the bigger picture: Car Feels Weak When Accelerating + Check Engine Light .
If the misfire does not seem limited to one cylinder, you may also want to check P0300, which means random or multiple cylinder misfires.
What P0302 Usually Means
P0302 does not point to one guaranteed failed part. It means the engine computer is detecting a misfire in cylinder 2.
In real life, that usually means there is an ignition problem, fuel delivery problem, air/fuel imbalance, or mechanical issue affecting that cylinder.
👉 Real-world tip: P0302 often ends up being a spark plug, ignition coil, injector, or wiring issue before it turns out to be something more serious.
Beginner takeaway: P0302 tells you which cylinder is misfiring, not exactly which part failed.
Not sure what your code means or want to compare it with others? Browse all OBD2 trouble codes for beginners .
What “Cylinder 2” Means
Cylinder 2 means the engine computer has identified the misfire on the cylinder the manufacturer labels as number 2.
The physical location of cylinder 2 depends on the engine design, so do not assume its exact position without checking your vehicle information.
If your scanner shows misfires across different cylinders instead of only one, see P0300 (Random/Multiple Cylinder Misfire Detected).
Why Misfires Matter
A misfire means the air-fuel mixture in a cylinder is not burning correctly. That can make the engine run rough and send unburned fuel into the exhaust.
If the problem continues, that extra fuel can overheat and damage the catalytic converter. That is one reason a P0302 code should not be ignored for long.
Over time, repeated misfires can contribute to catalyst-efficiency problems like P0420. In some cases, broader air/fuel issues can also overlap with codes like P0171 or P0175.
Most Common Causes of P0302
1. Worn spark plug on cylinder 2
This is one of the most common causes. If the spark plug is worn, fouled, or damaged, cylinder 2 may not fire correctly.
2. Weak or failing ignition coil
If the coil for cylinder 2 is weak or intermittent, the spark may be too weak to ignite the mixture properly.
3. Fuel injector problem
If the injector for cylinder 2 is clogged, sticking, or not delivering fuel correctly, that cylinder can misfire.
4. Wiring or connector issue
A damaged connector, loose wiring, or poor electrical connection can affect the spark plug, coil, or injector for that cylinder.
5. Vacuum leak or mixture problem
Air/fuel imbalance can make combustion unstable. Broader mixture-related issues can also trigger codes like P0171, or P0174.
6. Low compression or mechanical issue
Burned valves, head gasket issues, or internal engine wear can also cause a cylinder-specific misfire.
Can P0302 Cause Other Codes?
Yes. If the problem spreads or affects more than one cylinder, you may later see P0300.
If the misfire continues long enough, it can also damage the catalytic converter and contribute to codes like P0420.
In some cases, if the root cause is fuel- or air-related, you may also see lean or rich codes appear with it.
What a Scanner Can Help You See
Even a beginner-friendly scanner can help you avoid guessing.
- Stored and pending codes
- Whether the misfire is limited to one cylinder or not
- Freeze-frame data from when the fault was detected
- Whether fuel-trim or catalyst-related codes are present too
If you are still choosing your first scanner, see our Best OBD2 Scanners for Beginners .
Not sure whether a phone-based tool or standalone tool is easier? Read: Bluetooth vs Wired OBD2 Scanners
Can I Drive With a P0302 Code?
Sometimes yes — but be careful.
If the check engine light is flashing, the engine is shaking badly, or the car has clear power loss, you should avoid driving if possible.
If the light is solid and the car still runs mostly normal, short-term driving may be possible while you diagnose it, but you should not ignore it.
If you are unsure whether it is safe to keep driving, read: Can I drive with the check engine light on?
How Serious Is P0302?
Fairly serious.
P0302 is more serious than many simple emissions codes because it involves combustion problems, not just a sensor reading or a small leak.
If the misfire continues, it can:
- Cause rough running and poor acceleration
- Waste fuel
- Damage the catalytic converter
- Point to a larger ignition, fuel, or mechanical problem
Beginner rule: if the light is flashing or the engine is shaking hard, treat it as urgent.
Beginner Mistakes to Avoid
Replacing random parts without checking cylinder 2 first
P0302 already tells you which cylinder has the problem. Start there instead of guessing across the whole engine.
Ignoring a flashing check engine light
A flashing light is a strong clue that the misfire is active and more urgent.
Clearing the code before writing it down
Once you clear it, you lose useful clues like freeze-frame data and related codes.
Assuming it is always “just a spark plug”
Spark plugs are common, but ignition, injector, wiring, air/fuel, and mechanical issues can all cause P0302.
Beginner-Friendly Diagnosis Order
If you want to keep this simple, follow this order:
- Read and write down all stored codes
- Pay attention to whether the check engine light is solid or flashing
- Check the spark plug and ignition coil for cylinder 2 first
- Look for related fuel-trim or misfire codes
- Think about injector, wiring, or compression issues only after the basics
👉 Beginner move: start with the spark plug and ignition coil on cylinder 2 before jumping to expensive repairs.
Related misfire codes: P0300, P0301, P0303, P0304.
If you are seeing multiple misfire codes, start with P0300 to understand the overall problem first.
Frequently Asked Questions
What does P0302 mean?
It means the engine computer detected a misfire in cylinder 2.
Is P0302 serious?
Yes, it can be. An active misfire can make the engine run rough and can damage the catalytic converter if ignored.
Can bad spark plugs cause P0302?
Yes. Worn spark plugs are one of the most common causes, but coils, injectors, wiring, vacuum leaks, and low compression can also cause it.
Can I drive with a P0302 code?
If the light is flashing, the engine is shaking badly, or the car has clear power loss, avoid driving if possible. If the light is solid and the car runs mostly normal, short-term driving may be possible while you diagnose it.
Final Beginner Takeaway
P0302 means cylinder 2 is misfiring. The important part is this: the code tells you where the problem is happening, but not exactly which part failed.
Start simple: scan the car, write down all codes, and check the cylinder 2 spark plug and ignition coil before buying random parts.
If the engine is shaking hard or the light is flashing, treat it as more urgent than a simple emissions code.