P0302 on Mazda
Cylinder 2 Misfire Detected
P0302 on Mazda vehicles indicates cylinder 2 misfire detected. Au7o has documented this code across 7 Mazda models — most commonly on CX-3, CX-5, Mazda3. This code means the engine computer has detected a misfire specifically in cylinder 2, meaning that cylinder isn't completing combustion properly on some firing events. The computer watches tiny variations in crankshaft speed to spot when a cylinder fails to fire, and a misfire means the air-fuel mixture isn't igniting correctly — usually from a spark, fuel, or compression problem in that cylinder. You may feel a stumble, rough idle, shaking, loss of power, or a flashing check-engine light, and persistent misfires can damage the catalytic converter. Because it names a single cylinder, the fault is often a component serving just cylinder 2, like its coil, plug, or injector. Typical repair costs on Mazda range from $50 to $5,000, depending on the specific model and root cause.
Common Causes of P0302
- •Worn or fouled spark plug (cylinder 2)
- •Failed ignition coil or coil-on-plug (cylinder 2)
- •Clogged or faulty fuel injector (cylinder 2)
- •Vacuum or intake air leak affecting that cylinder
- •Low compression (worn rings, burnt/bent valve, head gasket)
- •Damaged spark plug wire or boot (if equipped)
- •Carbon-tracked or cracked coil/plug causing spark loss
- •Faulty PCM/ECM driver (rare)
P0302 on Mazda by Model
Mazda CX-3(1 issue)
- Skyactiv 2.0L Intake Valve Carbon Buildup2016-2021
The 2016-2021 Mazda CX-3 with the 2.0L Skyactiv-G direct injection engine develops carbon deposits on the intake valves over time. Because direct injection sprays fuel directly into the combustion chamber rather than over the intake valves, there is no fuel wash to clean the valve backsides. Oil vapors from the PCV (Positive Crankcase Ventilation) system coat the intake valves and bake into hard carbon deposits. This gradually restricts airflow, causing misfires on cold starts, loss of low-end power, and reduced fuel efficiency. Using conventional oils with high volatility worsens the problem by producing more PCV vapors.
Mazda CX-5(1 issue)
- Carbon Buildup on Intake Valves (Skyactiv)2013-2023
Direct-injection Skyactiv engines accumulate carbon deposits on intake valves due to oil vapors from the PCV system. Without port injection to clean valves, carbon can fuse to valve surfaces over time, typically appearing around 65,000+ miles.
Mazda Mazda3(1 issue)
- Carbon Buildup on Direct Injection Intake Valves2012-2025
SkyActiv direct-injection engines lack port injection to wash intake valves, causing carbon deposits to accumulate over time. Carbon buildup restricts airflow, causing rough idle, misfires, and power loss. Typically becomes noticeable around 60,000-80,000 miles.
Mazda Mazda6(1 issue)
- SkyActiv-G Intake Valve Carbon Buildup (Direct Injection)2014-2021
Because the SkyActiv-G direct-injection engine sprays fuel directly into the cylinder, no detergent fuel ever washes the back of the intake valves. Oil vapor drawn through the PCV system bakes onto the hot valve stems and accumulates as hard carbon, typically becoming noticeable on the 2.5L between 60,000 and 100,000 miles. The deposits restrict airflow and cause rough idle and cold-start misfires that are otherwise hard to diagnose.
Mazda MX-5 Miata(1 issue)
- Crankshaft Position Sensor Failure (NB)1999-2005
The NB Miata (1999-2005) crankshaft position sensor (CPS) is a known failure point. The sensor deteriorates from engine heat, causing intermittent stalling, no-start conditions, and random misfires. Failure is often heat-related - the car runs fine when cold but stalls or dies after reaching operating temperature.
Mazda RX-8(1 issue)
- Apex Seal Failure / Compression Loss2004-2012
The Renesis rotary engine in the RX-8 is infamous for apex seal wear and failure, leading to catastrophic compression loss. Apex seals maintain the combustion chamber seal between the rotor and housing. Heat, carbon deposits, and inadequate lubrication cause seals to wear, chip, or break. Compression testing below 6.5 kg/cm2 indicates rebuild is needed. This is the single most common and feared RX-8 issue.
Mazda Tribute(1 issue)
- Ignition Coil Failure and Misfires2001-2011
Ignition coil-on-plug coils fail causing misfires. Ford 3.0L Duratec V6 coils are prone to cracking and arcing. Usually fails one at a time.
Looking for P0302 on a different make?
View P0302 across all makes →Frequently Asked Questions
What does P0302 mean on Mazda?▼
P0302 stands for "Cylinder 2 Misfire Detected." This code means the engine computer has detected a misfire specifically in cylinder 2, meaning that cylinder isn't completing combustion properly on some firing events. The computer watches tiny variations in crankshaft speed to spot when a cylinder fails to fire, and a misfire means the air-fuel mixture isn't igniting correctly — usually from a spark, fuel, or compression problem in that cylinder. You may feel a stumble, rough idle, shaking, loss of power, or a flashing check-engine light, and persistent misfires can damage the catalytic converter. Because it names a single cylinder, the fault is often a component serving just cylinder 2, like its coil, plug, or injector. On Mazda specifically, this code is documented across 7 models.
What causes P0302 on Mazda vehicles?▼
Common causes on Mazda: Worn or fouled spark plug (cylinder 2), Failed ignition coil or coil-on-plug (cylinder 2), Clogged or faulty fuel injector (cylinder 2), Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/bent valve, head gasket). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0302 on a Mazda?▼
Repair costs on Mazda range from $50 to $5,000, depending on the specific model and root cause.
Which Mazda models have P0302 documented?▼
Au7o has documented P0302 on 7 Mazda models: CX-3, CX-5, Mazda3, Mazda6, MX-5 Miata, RX-8, Tribute.