P0302 on MINI: How to Diagnose & Fix
Cylinder 2 Misfire Detected
4 MINI models · 5 documented issues · 2 critical · $300-$3,000 repair
P0302 on MINI by model: symptoms, diagnosis and fix
The R56 Cooper S N14 engine (2007-2010) is particularly notorious for timing chain tensioner failure, even more so than the naturally aspirated N12. The higher cylinder pressures from turbocharging accelerate chain stretch and guide rail wear. The revised N18 (2011-2013) improved but didn't fully resolve the issue.
Common Symptoms
- Loud rattling on cold start
- Check engine light
- Reduced power
- Engine misfire codes
- Metal debris in oil
How to Fix
Replace timing chain, tensioner, guides, and sprockets. N14 engines should have this done proactively at 50-60k miles. N18 engines are better but should be inspected at 80k. Replace oil pump chain at the same time.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- MINI N14 timing-chain kit 11318618317KTOEMFCP Euro 11318618317KT / MINI 11318618317
VIN-confirmed N14 timing-chain, guide and tensioner failure branch Fitment/availability: The inspected direct U.S. Confirm VIN and kit contents before purchase; it is not the N18 branch a
- MINI N18 timing-chain kit 11318618318KT1OEMFCP Euro 11318618318KT1 / MINI 11318618318
VIN-confirmed N18 timing-chain, guide and tensioner failure branch Fitment/availability: The inspected direct U.S. Confirm VIN and kit contents before purchase; do not use it for N14 or
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Sources for this issue (3)
All turbocharged direct-injection MINI engines (N14, N18, B46/B48) accumulate carbon deposits on intake valves since fuel is injected directly into the cylinder rather than washing over the valves. This reduces airflow and causes rough running.
Common Symptoms
- Rough idle
- Hesitation on acceleration
- Reduced fuel economy
- Misfire codes
- Loss of power
How to Fix
Walnut blast the intake valves to remove carbon deposits. This should be done every 40-60k miles as preventive maintenance. Install an oil catch can to reduce oil vapor reaching the intake.
Sources for this issue (2)
The R56 Cooper's N12 engine suffers from premature timing chain tensioner and guide rail failure. The plastic chain guides deteriorate, causing chain slack that leads to rough running and potential catastrophic engine damage if the chain jumps timing.
Common Symptoms
- Rattling noise on cold start
- Check engine light
- Rough idle
- Loss of power
- Engine misfire
How to Fix
Replace timing chain, tensioner, and guide rails. Use updated BMW/MINI parts with revised guide rail material.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- MINI N12/N16 timing-chain kit 11318618318KTOEMFCP Euro 11318618318KT / MINI 11318618318
VIN-confirmed naturally aspirated N12/N16 timing-chain, guide and tensioner repair branch Fitment/availability: The inspected direct U.S. Confirm VIN and engine before purchase; it does not esta
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
- 2008 Mini Cooper engine complaints (CarComplaints, page 2)owner-complaints (NHTSA complaint mirror)
- Timing Tensioner Problems of Mini Cooperowner-complaints (NHTSA complaint aggregator)
- Mini Cooper Timing Chain Problems May Stem From Defectlegal investigation summary
All MINI JCW models with direct injection (N14, N18 and B48 engines) accumulate carbon deposits on the intake valves because fuel is injected directly into the cylinder rather than washing over the valves as in port injection engines. Over 30,000-50,000 miles, carbon buildup restricts airflow, causing rough idle, misfires, reduced power, and poor fuel economy. The N14 engine (2008-2012) is particularly susceptible due to its higher oil consumption contributing additional oil vapor to the intake tract.
Common Symptoms
- Rough or lumpy idle that smooths out at higher RPM
- Misfires under load or during cold start
- Noticeable loss of power and throttle response
- Decreased fuel economy by 2-4 MPG
- Check engine light with misfire codes (P0300-P0304)
How to Fix
Have a walnut shell blasting (media blasting) service performed every 30,000-40,000 miles to remove carbon deposits from the intake valves. This costs $300-600 at a MINI specialist. Installing an oil catch can on the PCV system slows carbon accumulation by preventing oil vapor from reaching the intake valves. For N14 engines with high oil consumption, address the oil consumption issue first to reduce the rate of carbon buildup.
Owner tips & cautions
- TipSchedule walnut blasting as regular maintenance every 30-40K miles — think of it like a timing belt on older cars. The cost of regular blasting ($400) is far less than the engine damage that severe carbon buildup can cause.
- TipInstall an oil catch can on the crankcase ventilation system — this is the single most effective mod for slowing carbon buildup on any direct-injection MINI engine.
Sources for this issue (3)
- Carbon Buildup in MINI Cylinder Head — MINI2.comowner-report
- N14 vs N18 Engine Comparison — Lohen MINIowner-report
- Common R56 MINI Problems — JCW Adventuresowner-report
Direct-injection turbo engines in MINI GP models can accumulate carbon deposits on intake valves because fuel does not wash the valve backs. Over time this can cause rough idle, hesitation, misfires, and reduced performance, especially noticeable on cold starts. This is widely documented in MINI owner reports, and MINI service bulletin SI M13 01 15 addresses carbon-related drivability complaints on the N18 engine used in the GP2.
Common Symptoms
- Rough idle, especially cold
- Hesitation on acceleration
- Misfire under load
- Reduced fuel economy
- Check Engine Light with misfire codes
How to Fix
Perform intake valve cleaning (walnut blasting or approved chemical/abrasive cleaning) and replace intake manifold gaskets as needed. Address contributing factors such as PCV system issues and ensure correct oil specification and change intervals; some owners add catch cans, but cleaning remains the primary fix.
Sources for this issue (1)
P0302 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0302 mean on a MINI?
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 MINI it is documented across 4 models: Cooper S, Cooper, John Cooper Works, GP.
What are the most common causes of P0302?
The most common causes of P0302 are: 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). The specific cause varies by vehicle.
How much does it cost to fix P0302 on a MINI?
Published repair estimates on MINI range from $300 to $3,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.