P0302 Code: Mazda CX-5 (2022-2024) - Causes, Symptoms & Fixes

P0302 diagnostic guide for 2022-2024 Mazda CX-5 (OBD-II)

Recalls/TSBs: No recalls found in NHTSA database for this make/model/year/issue. No official complaint data for this combination were provided in the data above. Data limitations mean this guide uses general Mazda/AWD four-cylinder engine knowledge plus standard OBD-II misfire troubleshooting principles.

CODE MEANING AND SEVERITY

• Code meaning: P0302 = Cylinder 2 Misfire Detected. The engine control module (PCM) senses that cylinder 2 is not producing the expected power or is misfiring (e.g., incomplete combustion).
• Severity/impact:
  • Symptoms may include rough idle, engine shaking, reduced power/acceleration, and possible check engine light.
  • Prolonged misfire can overheat a catalytic converter or lead to engine damage if the misfire is sustained and fuel delivery or ignition is repeatedly faulty.
  • On some drives, you may experience intermittent performance loss or stumble, especially under load or at specific RPMs.
• Note: The information here reflects general P0302 behavior on Mazda 2.5L SKYACTIV-G (and turbo variants) as applicable to 2022-2024 CX-5. Data provided shows no recalls or complaints for this exact combo.

COMMON CAUSES ON MAZDA CX-5 (P0302)

• Ignition system
  • Faulty ignition coil for cylinder 2 (coil-on-plug assembly). A weak or failed coil can fail to fire properly.
  • Worn or damaged spark plug in cylinder 2 (incorrect gap, fouling, oil contamination, or wear leading to weak spark).
  • Faulty coil boot/connector or damaged wiring to the coil.
• Fuel system
  • Clogged, sticking, or malfunctioning fuel injector on cylinder 2.
  • Low fuel pressure or drifting fuel rail pressure affecting cylinder 2.
  • Contaminated or dirty fuel or injector o-rings causing leakage.
• Air and vacuum
  • Vacuum leak around cylinder 2 (manifold gaskets, intake plenum, PCV system). A leak can lean out cylinder 2 and cause a misfire.
  • Intake manifold gasket or throttle-body issues affecting cylinder 2.
• Mechanical
  • Low compression in cylinder 2 due to worn piston rings, valve issues, or a faulty head gasket.
  • Timing chain/belt or cam timing issues (less common on these engines but possible in severe cases).
• Electrical/ECU
  • Damaged wiring harness, poor ground, or intermittent PCM sensor readings affecting combustion in cylinder 2.
  • Software/ECU update issues (rare; typically resolved by dealer software updates if applicable).
• Other
  • Oil intrusion into cylinder 2 (worn valve seals or piston ring problems) causing misfire and oil fouling on the plug.
  • Misfire interactions with turbocharging (in CX-5 with 2.5T): coil, injector, or boost-related issues can show up as cylinder-specific misfire.

SYMPTOMS

• Check Engine Light (CEL) or MIL with P0302 stored.
• Rough idle or engine shaking at idle, especially when stationary.
• Hesitation, lack of power, or reduced acceleration under load.
• Misfire may be smooth at steady highway speed but present at throttle changes.
• Possible mild fuel odor if unburned fuel enters exhaust, depending on duration.
• No universal symptom; the exact feel depends on whether the misfire is intermittent or constant and on engine variant (2.5L NA vs 2.5L Turbo).

DIAGNOSTIC STEPS (systematic approach)

Note: Start with the simplest, most common items and move toward more involved tests. If you’re uncomfortable with any step, seek professional service.

• Step 0: Verify the code

  • Use a scan tool to read the P0302 code and check freeze-frame data. Confirm that P0302 persists across two separate scans and note engine RPM, load, temperature, and ignition/fuel trims at the time of misfire.
  • Check for related codes (P0300, P0301, P0303, P0304, P0352, etc.).

• Step 1: Visual inspection

  • Inspect spark plug in cylinder 2: look for excessive wear, fouling (oil or fuel), or damage. Check gap if accessible.
  • Inspect ignition coil and its boot for cracks, oil contamination, or corrosion on the connector. Check wiring for cracks or loose connectors.
  • Inspect vacuum hoses nearby cylinder 2 for cracks or disconnections; check PCV valve and associated lines.
  • Inspect cylinder 2 fuel injector wiring/connectors for secure connection and any signs of corrosion or damage.

• Step 2: Swap/tests to identify the faulty component

  • Swap the ignition coil (or swap coils between two cylinders if you have a multi-coil setup) with another cylinder (e.g., swap coil 2 with coil 3). Clear codes and drive to see if the misfire follows the coil. If P0302 becomes P0303 after swap, the coil is likely bad.
  • If your vehicle uses spark plugs with coil-on-plug, you can also swap spark plugs between cylinder 2 and another cylinder to see if the misfire follows the plug.
  • If available, perform a noid light test or injector pulse test for cylinder 2 to verify injector operation. Listen for injector click with a stethoscope or use an injector test tool.
  • Check ignition coil primary/secondary resistance (per Mazda service data):
    • Primary resistance: roughly in the low ohms range (varies by coil design; typically around 0.5–2 ohms is common for many coils)
    • Secondary resistance: typically higher (tens of thousands of ohms, e.g., 6k–12k ohms)
    • If readings are out of spec, replace the coil.
  • Check fuel injector resistance for cylinder 2 (typical 12–16 ohms is common for many direct-injection injectors; refer to the service manual for exact spec). If out of spec, replace the injector or perform cleaning as needed.

• Step 3: Air and vacuum tests

  • Perform a vacuum/pressure test around cylinder 2 area. Spray around intake gaskets and PCV connections with a safe aerosol (carb spray) or smoke test to identify leaks. If misfire changes with spray, you’ve found a vacuum/air path issue.

• Step 4: Fuel and compression tests

  • Fuel pressure test: Verify rail pressure is within specification for engine variant (NA or turbo). Low pressure can cause misfires, especially under load.
  • Compression test: Compare cylinder 2 compression with other cylinders (within 10–15% is typical). If cylinder 2 is low, you may have ring/valve/head gasket issues.
  • If compression is good and no fuel/air faults are found, proceed to the next steps.

• Step 5: Data stream analysis

  • While the engine runs, check real-time data:
    • Short-term fuel trim (STFT) and Long-term fuel trim (LTFT). Abnormal trims can indicate injector, leak, or sensor issues.
    • Misfire counters in the live data (some scanners show misfire counts by cylinder).
    • Ignition coil current and injector control signals (where available).
  • If STFT/LTFT are normal but cylinder 2 misfires, it often points to ignition or injector issues rather than a large fuel trim problem.

• Step 6: Mechanical considerations

  • If all electronic tests pass and compression is normal, consider more in-depth mechanical inspection (valve timing check, camshaft/valve train condition) if other cylinders show similar symptoms or if compression is borderline.

• Step 7: Post-repair verification

  • After repairing or replacing components, clear the codes and run the engine through a few drive cycles to ensure the misfire does not return.
  • Confirm no new codes appear and that fuel trims are within normal range.

RELATED CODES

• P0300: Random/Multiple Cylinder Misfire Detected (often seen alongside P0302 if misfire pattern is not isolated).
• P0301, P0303, P0304: Cylinder-specific misfire codes for cylinders 1, 3, and 4, respectively.
• P0352: Ignition Coil B Primary/Secondary Circuit Malfunction (cylinder 2 coil circuit). Depending on Mazda coil mapping, the exact coil identifier may differ, but P0352 commonly relates to the ignition coil issue on cylinder 2.
• P035x family (other if applicable for nearby cylinders): coil circuit faults on other cylinders may be observed if a shared harness or power supply issue exists.
• Note: Diagnostic steps should verify whether misfire follows a particular coil or injector before concluding.

REPAIR OPTIONS AND COSTS (2025 PRICE RANGE)

Prices are estimates for typical 2025 US service in moderate-cost shops. Actual quotes vary by region, shop, and engine variant (NA vs turbo). Labor times are approximate.

• Spark plug replacement (4 plugs; recommended when investigating P0302)
  • Parts: $40–$120 ($10–$30 each for aftermarket; Mazda-appropriate iridium plugs tend to be higher)
  • Labor: 0.8–1.5 hours
  • Total: roughly $180–$450 (if doing all four plugs; doing only cylinder 2 is possible but most shops will replace all plugs at once)
• Ignition coil replacement (for cylinder 2)
  • Parts: $60–$180 (coil-on-plug unit)
  • Labor: $60–$140
  • Total: roughly $120–$320
• Fuel injector (cylinder 2)
  • Injector replacement
    • Parts: $120–$260
    • Labor: $60–$150
    • Total: roughly $180–$410
  • Cleaning/injector service (no replacement)
    • Parts: $0–$60
    • Labor: $40–$120
    • Total: roughly $40–$180
• Fuel system and fuel pressure service
  • Pressure test, possible rail seal or regulator service
  • Total: roughly $100–$250 (labor can be higher if leaks found)
• Vacuum/PCV system repair
  • Parts: $20–$60
  • Labor: $50–$120
  • Total: roughly $70–$180
• Compression issue repair (if found)
  • Head gasket/valve/seal work is major
  • Parts: hundreds to thousands
  • Labor: several to many hours
  • Total: widely variable; typically $1,000–$4,000+ depending on extent
• Software update or ECU reprogramming
  • Cost: sometimes free at a dealer or $50–$150 at independent shop
• Diagnostic fee
  • Typical: $80–$150 if not waived with repair
• Summary guidance
  • The most common, non-invasive fixes are coil or spark plug replacement and injector testing/cleaning.
  • If there is a mechanical issue (low compression), the repair cost rises dramatically.
  • A full set of plugs and a coil for cylinder 2 is a common starting point at a reasonable total cost.

DIY vs PROFESSIONAL

• DIY-friendly tasks (with appropriate tools and safety):
  • Visual inspection of coil boot, plug, and nearby hoses.
  • Swapping a coil or spark plug with another cylinder to see if misfire follows the component.
  • Basic injector testing with a stethoscope or noid light (if you have access to the proper tool).
  • Checking for vacuum leaks with spray method around the intake manifold and PCV lines.
  • Reading live data with a basic OBD-II scanner (fuel trims, misfire counters if supported).
• DIY caveats:
  • Avoid harming sensors or damaging coil boots; ensure engine is cool before removing spark plugs.
  • Some Mazda CX-5 configurations require specific tools or procedures for coil removal and plug replacement; refer to the service manual for torque specs and surge protection.
  • For turbo variants or advanced fuel system diagnostics, professional equipment and knowledge are recommended.
• Professional route:
  • If the misfire persists after basic checks, or if you suspect compression or valve issues, a professional diagnostic is advised.
  • A shop can perform a controlled coil/plug swap, precise injector testing, compression test, leak tests, and fuel pressure tests with the correct equipment.

PREVENTION

• Regular maintenance
  • Replace spark plugs at the manufacturer-recommended interval (often around 100,000 miles for modern Mazda engines, but verify for your exact build and spark plug type).
  • Use the recommended plug type and heat range for your engine; Mazda-original or equivalent equivalents are typically preferred.
  • Inspect ignition coils and harnesses at service intervals, especially if you note intermittent misfires.
• Fuel and air system care
  • Use quality gasoline; avoid frequent cheap fuel with high ethanol if the vehicle manufacturer cautions against it.
  • Replace air filters at recommended intervals to prevent unmetered air from affecting mixture stability.
  • Consider occasional injector cleanout if recommended by Mazda service guidelines or if fuel delivery symptoms appear (do not rely solely on fuel system cleaners as a cure for a mechanical fault).
• Monitoring and driving habits
  • Address misfires promptly; persistent misfires can damage catalytic converters and increase emissions.
  • When driving, avoid heavy loads for prolonged periods if you suspect a misfire issue, and seek diagnosis promptly to avoid downstream damage.
• Documentation and checks
  • Keep a record of any misfire-related codes and repairs; this helps with diagnosing recurring issues and ensures you aren’t chasing intermittent faults.

Data limitations

• The provided data indicates there are no NHTSA complaints or recalls for the 2022-2024 Mazda CX-5 with P0302 in the dataset. No recalls found in NHTSA database. This guide emphasizes general, non-recall-based diagnostic steps and Mazda-specific engine knowledge. If you have access to dealer service bulletins (TSBs) or updated Mazda service data, those may provide model-year and engine-specific guidance beyond this general guide.