P0302 Code: Cylinder 2 Misfire Detected
Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant getting in.
At a glance
Severity: Moderate
- Meaning
- Cylinder 2 Misfire Detected
- System
- Ignition & Misfire · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $80–$2,800
- DIY difficulty
- Moderate
P0302 means the engine computer has counted repeated misfires on cylinder 2. On an inline four, that is one of the two middle cylinders. It sits between cylinders 1 and 3, shares a thin strip of head gasket and coolant passages with both, and on older wasted-spark ignition systems it also shares a coil with cylinder 3. That makes cylinder 2 a common place for a head-gasket leak to show up first as a misfire, especially right after a cold start. On V engines, cylinder 2 is the first cylinder of the second bank on engines that alternate numbering (GM, Toyota) and the second cylinder of bank 1 on engines numbered bank by bank (Ford, Honda).
Can I keep driving? With a steady light you can drive carefully to a shop, but watch the temperature gauge and coolant level. A misfire caused by a head-gasket leak can turn into overheating. If the light flashes or the engine starts running hot, pull over and shut it off.
How to read P0302
- P Powertrain
- 0 Generic (SAE)
- 3 Ignition / misfire
- 02 Specific fault
Symptoms
- Rough idle, often worst in the first minute after a cold start
- Check-engine light on, flashing under heavy load
- Coolant level dropping with no visible leak (head-gasket cause)
- White, sweet-smelling exhaust at startup (head-gasket cause)
- Hesitation when accelerating and lower gas mileage
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Failing ignition coil or cracked boot on cylinder 2, or a shared 2/3 coil on wasted-spark systems
- Worn, cracked or fouled cylinder 2 spark plug
- Clogged or leaking cylinder 2 fuel injector
- Coolant seeping into cylinder 2 through a leaking head gasket or cracked head, especially if P0303 is also set
- Vacuum leak at the cylinder 2 intake runner
- Low compression from a burned valve, worn rings or a collapsed lifter
- Chafed wire or corroded connector at the cylinder 2 coil or injector
Diagnosis step by step
Screen for a coolant leak first
With the engine cold, check the coolant level in the reservoir and radiator, and ask yourself whether you have been topping it up. White, sweet-smelling exhaust at startup, or a misfire that only happens during the first minute of a cold start, strongly suggests coolant is getting into the cylinder overnight.
Tools: Flashlight
Read the cylinder 2 spark plug
Pull the plug and compare it with cylinder 1 or 3. A plug that looks steam-cleaned and unusually white compared with its neighbors points to coolant. A wet, black plug points to fuel or ignition, and an oily one points to rings or valve seals.
Tools: Spark plug socket, Flashlight
Swap the coil, or test the coil pack
On coil-on-plug engines, swap coil 2 with coil 1 and see whether the misfire moves. On wasted-spark coil packs, cylinders 2 and 3 share one coil tower pair, so a bad pack usually misfires both. Check the secondary resistance of that pair with a multimeter and compare it with the 1/4 pair.
Tools: Screwdriver, Multimeter, OBD-II scanner
Pressure-test the cooling system
If you suspect coolant, pressurize the cooling system to the cap rating (usually around 15–18 psi) and watch whether the pressure falls. Then pull the cylinder 2 plug and look for coolant in the cylinder. A shop can also test the coolant for combustion gases, which confirms a head-gasket breach.
Tools: Flashlight
Compression and leak-down on cylinders 2 and 3
Test both middle cylinders. Two adjacent cylinders reading low by a similar amount point to a gasket failure between them. If a leak-down test on cylinder 2 makes bubbles in the coolant reservoir, that confirms it.
Tools: Compression tester
Check injector 2 last
If the ignition and sealing checks pass, listen to injector 2 and compare its resistance with the others. A clogged injector gives a lean, whitish plug with no coolant loss, which is different from what a gasket leak looks like.
Tools: Multimeter
Where the parts are
- 1Ignition coil
- 2Spark plug
- 3Fuel injector
- 4Camshaft sensor
- 5Crankshaft sensor
- 6Engine computer (ECM)
- 7Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace cylinder 2 ignition coil (or wasted-spark coil pack) | Yes | $90–$350 |
| Replace spark plugs (full set) | Yes | $120–$450 |
| Cooling system pressure test and combustion-gas test | No | $80–$200 |
| Replace cylinder 2 fuel injector | No | $200–$600 |
| Replace head gasket (inline four, head machined as needed) | No | $1,300–$2,800 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Field data
| Ford | 191 | ||
|---|---|---|---|
| Honda | 46 | Cr-V, Odyssey, Accord | |
| Jeep | 22 | Grand Cherokee, Wrangler Unlimited, Wrangler | |
| Hyundai | 19 | ||
| Dodge | 18 | Grand Caravan, Durango, Journey | |
| Kia | 16 | ||
| Chrysler | 15 | Town And Country, Pacifica, 200 | |
| Toyota | 8 | Camry, Prius V, Avalon |
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
A stored P0302 with the check-engine light on means an automatic fail at an OBD smog check. If the cause turns out to be a head gasket, fix it before testing, because clearing the code without a repair only buys a few miles.
Frequently asked questions
Why does cylinder 2 only misfire right after a cold start?
Something that changes as the engine warms up is involved. The classic cause is coolant seeping past a failing head gasket overnight, which makes the plug misfire until the coolant burns off. On direct-injection engines, carbon on the intake valves can cause a similar cold-only misfire.
I have P0302 and P0303 together. What does that mean?
On an inline four, cylinders 2 and 3 are neighbors. A shared coil on wasted-spark systems, or a head gasket leaking between the two middle cylinders, can take out both at once. Test the coil pack and the compression of both cylinders before replacing anything else.
Can a bad coil on cylinder 2 damage anything else?
Driving for weeks with a misfire washes oil off the cylinder wall with raw fuel and can overheat the catalytic converter. The coil itself is cheap to replace, and the collateral damage is what gets expensive.
The plug looks perfectly clean. Isn't that good?
Not when it's cleaner than all the others. A spotless, bright-white plug in one cylinder often means coolant is steam-cleaning it. Compare it with the neighboring plugs and check the coolant level.