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What P0304 means for your Toyota Camry
Your Camry's ECM detected that cylinder 4 isn't firing properly - the crankshaft position sensor saw the rotational speed dip slightly each time cylinder 4 was supposed to combust. On the Camry four-cylinder, P0304 (cyl 4 at the transmission end) is most commonly a worn coil or fouled plug. On the V6, cyl 4 is rear-bank and harder to access.
🎯 Top Causes on the Toyota Camry
55%
#1 CAUSE
Cylinder 4 Ignition Coil Failure
Cyl-4 sits at the transmission end of the 2AR-FE and 2AZ-FE engines. Heat-soak from the firewall area accelerates Denso coil breakdown around 80k-130k miles. Coil swap test with cyl-2 takes 10 minutes. OEM Denso 90919-02258 or NGK U5099. Replace all four together if any one has failed and the car is over 100k miles.
OEM Coil
$80-$120
Aftermarket
$45-$70
w/Labor
$120-$280
25%
#2 CAUSE
Oil-Fouled Plug (2AZ-FE)
2007-2009 2AZ-FE engines burn oil due to piston ring design (covered by TSB T-SB-0094-11). The cyl-4 plug commonly fouls first or worst because cyl 4 cools the slowest and oil residue burns into the electrode. Inspect plug for wet oil deposits. Fix is plug replacement + ring repair under warranty if your VIN qualifies (10 yr / 150k mi). Outside warranty, ring repair is $3000-$5000.
Plugs (set 4)
$30-$60
Ring Repair (TSB)
$0 (qualifying VIN)
Out-of-Pocket Ring Repair
$3000-$5500
20%
#3 CAUSE
Rear-Bank Coil / Intake Manifold (V6)
On the 3.5L 2GR-FE V6, cyl 4 is on the rear bank (firewall side) - harder to access because the upper intake plenum must be removed. The rear-bank coils run hotter and tend to fail sooner than front-bank coils. Budget 2-3 hours of labor for a rear-bank coil job, or DIY with patience. Also check for vacuum leaks at the rear intake gasket - common on aging 2GR-FE.
Rear-Bank Coil
$80-$120
Intake Gasket
$40-$90
w/Labor
$280-$500
🚗 Most Affected Camry Model Years
| Year | Engine | Primary Cause | Typical Mileage | Notes |
|---|---|---|---|---|
| 2010-2017 | 2.5L 2AR-FE | Coil pack | 80k-130k | Most reliable |
| 2007-2009 | 2.4L 2AZ-FE | Oil-fouled plug | 90k-160k | TSB T-SB-0094-11 may cover |
| 2018+ | 2.5L A25A-FKS | Coil | 60k-90k | Newer DI engine |
| 2007-2017 | 3.5L 2GR-FE V6 | Rear-bank coil | 80k-130k | Cyl 4 is rear-bank; harder access |
🔧 How to Diagnose P0304 on a Toyota Camry
- Swap cyl-4 coil with cyl-2 on the 4-cylinder. On the V6, swap cyl-4 with cyl-6 (both rear bank). Clear code, drive. Misfire follows = bad coil.
- Pull cyl-4 plug and inspect. Oil-fouled on a 2007-2009 2AZ-FE = check VIN against oil-consumption TSB. Replace all four plugs as a set.
- On V6, if both coil and plug check good, leak-down test cyl-4. Also visually inspect the rear-bank intake manifold gasket for any oil seepage - a known wear point on high-mileage 2GR-FE.
Want a step-by-step walkthrough specific to your Toyota Camry? Run a $5.99 AI diagnosis report - we narrow the cause to your year, engine, and symptoms.
❓ Frequently Asked Questions
How serious is P0304 on a Camry?
Same severity as P0301/P0302/P0303 - moderate with a steady CEL, urgent with a flashing CEL. Cyl 4 dumps raw fuel into the cat just like any other misfire, so don't put off the fix.
How much does it cost to fix P0304 on a 4-cyl Camry?
Coil + plug (DIY): $80-$140 in parts. Shop: $180-$320. If you replace all 4 coils preventively because the car is over 100k miles, add $120-$200 for the extra three coils.
Why is cyl 4 misfire harder to fix on a V6 Camry?
On the 3.5L 2GR-FE, cyl 4 is on the rear bank against the firewall. Reaching it requires removing the upper intake plenum, fuel rail covers, and sometimes the wiper cowl. It's still doable as DIY (2-3 hours), just much more involved than the front-bank work.
Which cylinder is cylinder 4 on a Camry?
On the 4-cylinder (2AR-FE, 2AZ-FE), cyl 4 is at the transmission end of the engine - left side as you face the engine from the front. On the V6 (2GR-FE), the rear bank is cyls 2-4-6 and cyl 4 is the middle cylinder of the rear bank.
Can a clogged EGR cause P0304?
Possibly. A stuck-open EGR valve dumps exhaust into one cylinder more than others depending on intake geometry. On the 2GR-FE V6 with EGR, this can cause cyl-4 (rear bank) to misfire under load. Worth cleaning the EGR ($0-$30 in carb cleaner) if coil/plug come up clean.
See all P0304 causes (all vehicles) → · Related: Toyota 2AR-FE Coil Failure Pattern →