OBD-II code · vehicle-specific
On this page
- How this differs from the generic P0300
- Camry-specific diagnostic order
- 1. Pull all stored codes
- 2. Check coil and plug service history
- 3. Inspect coils — swap test
- 4. Check for intake-valve carbon (2018+ A25A direct injection)
- 5. Inspect VVT-i oil control valve
- 6. 2AZ head-bolt check (2007–2009 2.4L only)
- Camry-specific costs
- Common mistakes on Camry P0300
- How to reset after a Camry P0300 repair
- Related guides
P0300 in Toyota Camry (2.4L 2AZ-FE, 3.5L 2GR-FE)
How this differs from the generic P0300
The generic P0300 page treats P0300 as a broad
"random misfire" symptom with many possible causes. On the Toyota
Camry across recent generations, the cause distribution narrows:
2007–2017 Camry (2AZ-FE 2.4L, 2GR-FE 3.5L, 2AR-FE 2.5L port injection):
- Worn coils or plugs: ~55%
- Vacuum leak (VVT-i oil control valve): ~10%
- Fuel injectors: ~10%
- 2AZ stripped head bolts: ~10%
- Other: ~15%
2018+ Camry (A25A-FKS / A25A-FXS 2.5L direct injection):
- Worn coils or plugs: ~50%
- Carbon on intake valves: ~25%
- Fuel injectors (GDI): ~10%
- Other: ~15%
The 2007–2009 2.4L 2AZ-FE has a documented head-bolt problem —
the bolts can pull out of the aluminum block under heat cycling,
causing a slow coolant leak and eventual misfire. If you're working
on a 2007–2009 2.4L with P0300, head-bolt service should be on the
suspect list.
Camry-specific diagnostic order
1. Pull all stored codes
A single-cylinder code (P0301–P0306) alongside
P0300 points to one cylinder, not the random pattern. Lean codes
(P0171/P0174) point to vacuum
leaks. Fix specific codes first.
2. Check coil and plug service history
Toyota's factory service interval for iridium spark plugs is 120,000 miles. Most owners take Camry plugs to 100k+. After that interval, gap erosion makes the coil work harder, and the next misfire is a matter of time.
If plugs are at or past 100k miles, replace all 4 (4-cylinder) or all 6 (V6) plugs as a maintenance item, not as a guess. Use Denso SK20HR11 (2AZ) or equivalent NGK iridium.
3. Inspect coils — swap test
If P0300 appears intermittent and freeze-frame shows it across
multiple cylinders, swap two coils and watch which cylinder follows.
A coil that moves the misfire from random to specific identifies the
weak one.
Camry coils are slightly more durable than Civic or Corolla coils; expect 100,000+ miles before first failures appear. Replace as needed, not preemptively.
4. Check for intake-valve carbon (2018+ A25A direct injection)
The A25A series uses direct injection without a port-injector fallback. Intake valves cake with carbon after 60,000–80,000 miles because fuel never washes them. A walnut-blast service or BG GDI induction service can restore performance.
Pre-2018 Camrys are port-injected — fuel cleans the back of the valves during normal operation. Carbon buildup is not the issue.
5. Inspect VVT-i oil control valve
The variable valve timing oil control valve (OCV / VVT solenoid) can develop oil-pressure issues that affect cam timing and create misfires at specific RPM. A scan tool with VVT live data shows actual vs commanded timing — large mismatch confirms the valve.
6. 2AZ head-bolt check (2007–2009 2.4L only)
A torque-wrench check on accessible head bolts won't reveal pulled threads, but coolant loss without visible external leaks is the indirect indicator. Combined with P0300 and high mileage, head-bolt service should be priced before any major engine work.
Camry-specific costs
| Fix | DIY parts | Shop total |
|---|---|---|
| Replace all spark plugs (4-cyl) | $30–$80 | $150–$300 |
| Replace all spark plugs (V6) | $50–$120 | $250–$500 |
| Replace one ignition coil | $30–$80 | $120–$300 |
| Replace all coils (4-cyl) | $120–$320 | $400–$700 |
| Replace VVT-i oil control valve | $80–$200 | $200–$500 |
| Walnut-blast intake valves (2018+ GDI) | $300–$500 | $400–$900 |
| Replace fuel injectors (V6, all 6) | $300–$600 | $700–$1,400 |
| 2AZ head-bolt repair (2007–2009 2.4L) | n/a | $1,800–$3,500 |
For a 100k+ mile Camry with no maintenance history, a preventive
plug-and-coil service at $300–$600 total often eliminates the
P0300 and several related codes at once. This is the highest-value
preventive repair on these platforms.
Common mistakes on Camry P0300
- Replacing plugs without coils on high-mileage engines. Old coils strained by worn plugs are often the next failure. Doing both at once is the cheaper labor outcome.
- Skipping the GDI carbon-blast option (2018+). Direct-injection carbon buildup is real and reversible; ignoring it leads to recurring misfires after coil/plug replacement.
- Using non-Denso plugs on the 2GR-FE V6. Some non-OEM iridium plugs run shorter heat ranges than expected and foul faster on short-trip duty.
- Replacing the cat after a misfire. The misfire damaged the cat; fix the misfire first and reassess in 1,000 miles before spending on a cat.
How to reset after a Camry P0300 repair
Clear with a scan tool, drive 100 miles of mixed conditions. The misfire monitor on Toyota platforms runs continuously, so the code either clears within 5–10 miles or returns immediately to confirm fault. Recurring misfire counts also appear in scan-tool Mode 6 data for individual cylinders.