P0302 Code: Toyota Tacoma (2016-2023) - Causes, Symptoms & Fixes

Here is a comprehensive diagnostic guide for OBD-II code P0302 (Cylinder 2 Misfire Detected) specifically for 2016–2023 Toyota Tacoma. Important data note: the provided NHTSA data shows no owner complaints or recalls for this combination. No recalls found in NHTSA database. All cost estimates for 2025 are typical ranges based on common labor rates and parts pricing; actual prices will vary by region and shop.

CODE MEANING AND SEVERITY

• What the code means: P0302 indicates the PCM detected a misfire on Cylinder 2. A misfire means the cylinder did not ignite properly or at all during one or more engine cycles.
• Severity and potential consequences:
  • Mild/occurring misfire: rough idle, reduced power, and lower fuel economy; may set P0302 and/or contribute to P0300 (random misfire) if it becomes persistent.
  • Prolonged misfire: unburned fuel can cause overheating of the catalytic converter and potential damage; continued misfires can lead to catalytic converter failure or engine damage if ignored.
• Data limitations: No official complaint or recall data specific to this code for the Tacoma is provided here; the guide uses general diagnostic best practices suitable for this platform.

COMMON CAUSES ON TOYOTA TACOMA

The likely causes fall into ignition, fuel, air, and mechanical categories. For Cylinder 2 specifically:

• Ignition system
  • Worn or fouled spark plug in cylinder 2
  • Faulty ignition coil for cylinder 2 (coil-pack or coil-on-plug)
  • Damaged spark plug boot or ignition wiring to cylinder 2
• Fuel system
  • Malfunctioning or dirty fuel injector for cylinder 2
  • Low or irregular fuel pressure affecting injector performance
  • Contaminated or wrong-grade fuel affecting combustion in cylinder 2
• Air and vacuum
  • Vacuum leak near the intake port or around cylinder 2 (intake manifold gasket, vacuum hoses, PCV system)
  • Dirty or clogged air intake pathway affecting flow to cylinder 2
• Mechanical
  • Low compression in cylinder 2 due to valve, head gasket, piston, or ring issues (less common but possible)
  • Timing-related issues (rare for a single cylinder misfire, but possible if timing components are failing)
• Electrical/ECM related (less common)
  • PCM/driver circuitry issue or retained misfire data from cylinder 2 (usually accompanied by other codes)

SYMPTOMS

• Engine runs rough or shakes at idle; smoother at higher RPMs
• Noticeable loss of power or sluggish acceleration
• Reduced fuel economy
• Check Engine Light (CEL) with P0302 active or pending; possible intermittent misfire
• Occasional hesitation or stumbling, especially when engine is cold or under load
• If the misfire is severe, you may also see knock/RPM fluctuations or an audible miss in some conditions

DIAGNOSTIC STEPS

A structured approach to confirm and isolate Cylinder 2 misfire:

Preliminaries

• Retrieve and review the freeze frame data and any related codes (P0300 and other P0301–P0306 codes if present).
• Ensure battery voltage is healthy and the engine is in good operating temperature.

Step 1: Visual and quick checks

• Inspect spark plug 2 and ignition coil boot for damage, oil fouling, or carbon tracking.
• Check for damaged or loose spark plug wire/coil connector (even in COP systems, a damaged connector can cause misfires).
• Inspect surrounding vacuum hoses for cracks or leaks near cylinder 2 region.

Step 2: Spark plug testing/replacement (Cylinder 2)

• If plug 2 is fouled, oil-soaked, or worn, replace it. Use the plug type specified by Toyota for that engine (gap and heat range matter).
• If you’re only addressing cylinder 2, you can replace just that plug; otherwise, replacing all plugs is common practice for multi-cylinder misfires and can prevent future misfires.
• After replacement, clear codes and perform a drive cycle to see if the misfire returns.

Step 3: Ignition coil testing (Cylinder 2)

• Use a spark tester or swap the cylinder 2 coil with another cylinder’s coil (e.g., swap 2 and 4 coil) and recheck. If the misfire follows the coil, the coil is the cause; if it stays on Cylinder 2, the coil is likely fine and you should investigate spark plug, injector, or compression.
• Inspect the coil connector and wiring for signs of damage.

Step 4: Fuel injector testing (Cylinder 2)

• Check Resistance spec for injector 2 and compare to a reference value; a significant deviation can indicate a bad injector.
• Use a noid light to verify that injector 2 is receiving a proper injector pulse signal from the PCM when the engine is cranking/ running.
• Swap injectors between cylinders (e.g., 2 and 4) to see if the misfire follows the injector. If it does, the injector is faulty.
• If injector 2 is suspect but you don’t want to replace it yet, consider using a cleaner or fuel system additive as a temporary measure; however, active misfire should be properly diagnosed.

Step 5: Fuel system and fuel pressure

• Check fuel pressure with a suitable gauge and compare to Toyota service data for your engine. Low pressure can cause misfires or poor performance on multiple cylinders.
• Check for a clogged fuel filter (if applicable in your model year) and ensure the fuel pump is delivering consistent pressure.

Step 6: Air intake and vacuum integrity

• Perform a smoke test or spray test around the intake manifold and around cylinder 2 area while the engine is running; a change in idle suggests a vacuum leak.
• Inspect the PCV system for leaks or sticking PCV valve.

Step 7: Compression test and mechanical health

• If ignition and fuel systems test OK but misfire persists, perform a compression test on all cylinders, paying close attention to Cylinder 2.
• If Cylinder 2 has notably lower compression, perform a leak-down test to identify exact mechanical issue (valve sealing, piston ring condition, head gasket).

Step 8: Reassessment and road test

• After repairs, clear codes, and run through a thorough drive cycle across RPM/load ranges to confirm P0302 is resolved.
• If misfire reappears intermittently under certain loads, revisit injector, wiring, and vacuum checks; persistent misfires may require professional diagnosis.

Tips

• Be mindful of safety and proper PPE when working around hot engines.
• Do not drive aggressively with a known misfire for an extended period, as unburned fuel can damage the catalytic converter.
• Document all tests you perform and the outcomes; this helps when consulting a professional.

RELATED CODES

• P0300: Random/Multiple Cylinder Misfire Detected (often when multiple cylinders show misfire history or P0302 is accompanied by another P030x)
• P0301: Cylinder 1 Misfire
• P0303: Cylinder 3 Misfire
• P0304: Cylinder 4 Misfire
• P0305: Cylinder 5 Misfire
• P0306: Cylinder 6 Misfire
• In a 6-cylinder Tacoma, any P030x can be seen; always inspect the code set and check for other related trouble codes (e.g., P0171/0174 for fuel trim, or misfire-related fuel system fault codes)

REPAIR OPTIONS AND COSTS (2025 PRICES)

Prices vary by region, shop, and engine option (2.7L 4-cyl vs 3.5L V6). The Tacoma commonly uses coil-on-plug ignition and individual spark plugs; below are ballpark ranges for 2025.

• Diagnostic time (variable, typically 0.5–2 hours)
  • Cost range: approximately $60–$180 (labor). Some shops may roll diagnostic time into the repair estimate.

A. Spark plug replacement (Cylinder 2 only)

• Parts: Spark plug (OEM or equivalent): roughly $6–$25
• Labor: about 0.5–1 hour (if coil removal is required, it’s included)
• Estimated total: $100–$180

B. Ignition coil replacement (Cylinder 2)

• Parts: Coil pack or COP coil: $40–$120
• Labor: 0.5–1 hour
• Estimated total: $100–$250

C. Spark plug + ignition coil replacement (common combined repair)

• Parts: Plug + coil: ~$50–$150
• Labor: ~1–1.5 hours
• Estimated total: $150–$350

D. Fuel injector replacement (Cylinder 2)

• Parts: Fuel injector: $120–$350
• Labor: 0.5–1.5 hours
• Estimated total: $260–$700

E. Fuel system/pressure checks or cleaning (as needed)

• Parts: Vacuum hoses, gaskets, or clamps: $10–$60
• Labor: 0.5–1 hour
• Estimated total: $100–$300

F. Vacuum leak repair near cylinder 2

• Parts: Gaskets, hoses: $10–$80
• Labor: 1–2 hours
• Estimated total: $150–$450

G. Mechanical issue causing low compression (valve, piston, head gasket)

• Parts: Dependent on component; could range from gasket sets to full rebuild
• Labor: 4–12+ hours
• Estimated total: $1,000–$4,000+ (highly variable depending on extent)

H. PCM/ECM fault (rare)

• Parts: Reprogramming or replacement: $150–$1,000
• Labor: 0.5–2 hours
• Estimated total: $200–$900

Notes on costs:

• Turbocharged or high-compression variants can slightly alter pricing.
• Labor times vary; some shops charge flat minimums for diagnostic labor.
• For many Tacomas, replacing all spark plugs and coils at regular intervals is a preventative measure and can reduce future misfire risk.

DIY VS PROFESSIONAL

• DIY suitability:
  • Do-it-yourself is reasonable for spark plug and coil testing/replacement, especially on 2.7L 4-cyl Tacomas with easier access to cylinder 2 components.
  • If you’re comfortable with basic hand tools, some fuel injector testing, and reading OBD-II data, you can perform initial diagnosis.
  • Important: misfire can damage the catalytic converter if driven aggressively; if you’re unsure, seek professional help.
• When to go pro:
  • If you’re not experienced with ignition/fuel systems or if compression testing is needed.
  • If the misfire persists after swapping plugs/coils or injector testing.
  • If you suspect a mechanical issue (low compression, valve issues, head gasket).
  • If you need accurate fuel pressure testing or injector pulse testing, which requires specialized equipment.
• Safety note:
  • Always disconnect the battery when removing ignition components as needed; be mindful of airbag and electrical safety in modern Tacomas.

PREVENTION

• Regular maintenance:
  • Replace spark plugs at the manufacturer’s recommended interval for your engine (typical Toyota intervals range up to 100k–120k miles depending on engine and plug type).
  • Replace ignition coils only when failing tests or when indicated by diagnostics; faulty coils often show up as misfires across multiple cylinders.
  • Schedule routine fuel system maintenance and use high-quality fuel to avoid deposits and injector buildup.
  • Keep the air intake, throttle body, and vacuum system clean; fix vacuum leaks promptly.
  • Perform periodic compression tests if you notice running issues, particularly in engines with higher mileage.
• Driving habits:
  • Avoid extended periods of driving with a known misfire; if misfire occurs frequently, address it promptly to protect the catalytic converter and engine.
  • Use a high-quality fuel and a reputable fuel system cleaner occasionally if recommended by your technician.
• Documentation:
  • Maintain service history; note when misfire symptoms started and what diagnostics/tests were performed to help future technicians.

Data transparency and limitations

• The guidance above is informed by general OBD-II misfire diagnosis practices applied to Toyota engines in Tacoma models from 2016–2023. The provided data from NHTSA shows no owner complaints and no recalls for this specific combination, so the guide does not rely on complaint or recall data. If new recall or TSB information appears, it should be reviewed and incorporated.

If you’d like, I can tailor this guide further to your exact engine option (2.7L 4-cyl vs 3.5L V6) and provide a more detailed, step-by-step diagnostic checklist with expected resistance and voltage specs for the specific cylinder 2 injector, coil, and plug used in your model year.