P0302 on Hyundai: How to Diagnose & Fix
Cylinder 2 Misfire Detected
5 Hyundai models · 5 documented issues · 3 critical · $300-$7,500 repair
P0302 on Hyundai by model: symptoms, diagnosis and fix
The Theta II GDI engine in 2014-2015 and 2018-2019 Tucson models is susceptible to connecting rod bearing failure caused by manufacturing debris restricting oil flow. This can lead to catastrophic engine seizure, often without warning. Under the Theta II engine class-action settlement, Hyundai extended the powertrain warranty to a Lifetime Warranty (Warranty Extension TXXI) for connecting rod bearing damage on vehicles that complete the Knock Sensor Detection System software update (Service Campaign 953).
Common Symptoms
- Metallic knocking from engine
- Engine stalling without warning
- Check engine light with P1326 code
- Loss of power while driving
- Excessive oil consumption
How to Fix
Check VIN for active recalls at NHTSA.gov. Ensure the Knock Sensor Detection System (KSDS) software update has been installed - this monitors for early signs of bearing failure and can put the engine in limp mode. If the engine has failed from connecting rod bearing damage after the KSDS update, Hyundai covers the short-block repair under the lifetime warranty extension. Out-of-warranty replacement runs $4,500-7,500. Use full synthetic 0W-20 oil and change every 5,000 miles.
Owner tips & cautions
- TipGet the KSDS software update immediately if not already done - it can detect bearing failure early and prevent catastrophic seizure
- WarningIf you hear any knocking noise, stop driving immediately. Continued driving can destroy the engine beyond repair
Sources for this issue (1)
The 1.8L Nu engine in 2011-2016 Elantras is prone to premature failure due to manufacturing defects including a piston defect that produces piston slap/scuffing (most often in cold weather), connecting rod bearing failure, and oil passage problems. Metal debris from failed components can circulate through the engine causing catastrophic damage. A class action settlement (Brown v. Hyundai) extended the powertrain warranty on the engine long block for piston-slap damage to 10 years/120,000 miles for original owners and 8 years/80,000 miles for other owners in cold-weather states (campaign TXXK).
Common Symptoms
- Engine knocking or ticking noise that increases with RPM
- Excessive oil consumption
- Check engine light illumination
- Oil pressure warning light
- Engine stalling or loss of power
- Metal shavings in oil
How to Fix
Check for coverage under the Nu Engine Settlement warranty extension (Hyundai campaign TXXK, TSB 22-EM-009H) by giving a Hyundai dealer the VIN. Complete engine replacement if bearing failure has occurred.
Owner tips & cautions
- TipRegular oil changes every 3,000-5,000 miles to minimize sludge buildup.
- WarningThis is a high-severity issue - ignoring it can lead to costly repairs or safety concerns. Address it promptly.
- TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
Sources for this issue (4)
- Hyundai TSB 22-EM-009H - 1.8L Nu Engine Warranty Extension (TXXK)tsb
- Hyundai dealer notice - Brown Nu Class Action/Warranty Extension TXXKtsb
- MyCarVoice: Hyundai Elantra 1.8L Nu Engine Class Action Settlementmedia
- Sauder Schelkopf: Hyundai Elantra and Kia Forte Nu Engine Failures Class Action Investigationmedia
The direct-injected (GDI) 3.8L and 5.0L engines in the 2012+ Genesis accumulate carbon deposits on the intake valve faces. Since fuel is injected directly into the cylinder rather than over the intake valves, there is no fuel washing action to clean the valve backs. Carbon deposits restrict airflow, cause rough idle, misfires, and reduce power output. The problem is progressive and becomes noticeable around 40,000-60,000 miles. Short-trip driving and extended idle time worsen the buildup.
Common Symptoms
- Rough idle that smooths out after engine warms
- Misfires at idle or low RPM
- Reduced power output and throttle response
- Reduced fuel economy (2-4 MPG drop)
- Check engine light with random misfire codes
How to Fix
Walnut shell blasting of the intake valves is the most effective cleaning method — the intake manifold is removed and crushed walnut shells are blasted through the intake ports to remove carbon. This should be done every 40,000-60,000 miles as preventive maintenance. Chemical cleaning products (CRC GDI Cleaner) provide a partial solution between blastings. Some owners install an oil catch can to reduce the PCV oil vapor contributing to carbon buildup.
Owner tips & cautions
- TipSchedule walnut shell blasting every 50,000 miles — this is preventive maintenance on ALL GDI engines, not just when symptoms appear
- TipUse Top Tier gasoline (Shell, Chevron, Costco) — the higher detergent levels help reduce intake tract deposits even on GDI engines
Sources for this issue (2)
On the 2.5L Smartstream GDI+MPI engine (G4KN) used in the TM Santa Fe from 2021, the internal filter/screen inside the direct injector can break apart and the injector leaks fuel into the cylinder after shutdown and at idle. Owners report a hard hot start, raw-fuel smell, rough idle, single- or multi-cylinder misfires, loss of power and stalling while driving; the leaking fuel also dilutes the engine oil. Hyundai addressed it with TSB 23-FL-002H-1, which lists the diagnosis and replacement procedure for internally leaking GDI injectors and was later expanded to a wider production date range covering Santa Fe, Tucson and Santa Cruz. A 2025 class action alleges Hyundai has still not recalled the vehicles. Note the earlier 2.4L Theta II GDI injectors are a different part and this pattern is specific to the 2.5L.
Common Symptoms
- Long crank / hard hot start
- Rough idle and shaking at stop
- Misfire, flashing check engine light
- Sudden loss of power or stalling while driving
- Fuel smell; oil level rising and smelling of gasoline
How to Fix
Pull misfire DTCs and identify the offending cylinder(s). TSB 23-FL-002H-1 has been superseded by TSB 25-FL-001H (January 2025), which calls for replacing all four GDI injectors with Hyundai's injector kit (injectors, clips, high-pressure fuel pipe and gaskets) on affected vehicles. Change the engine oil afterward — fuel dilution from the leak contaminates it. Powertrain warranty covers this on most affected vehicles; push for the TSB by number if the dealer resists.
Sources for this issue (3)
The 2013 facelift switched the 3.8 Lambda V6 from port injection to gasoline direct injection. Because GDI sprays fuel straight into the cylinder, no fuel washes the back of the intake valves, and crankcase vapor routed through the PCV system bakes onto them. Owners report rough idle, misfires, and dulled throttle response typically starting around 60,000-90,000 miles. This is a clean generation split: the 2010-2012 port-injected 3.8 does not accumulate valve deposits this way, so a pre-facelift car is not exposed to this failure at all. Cylinder-specific misfires and lean bank codes are the usual first symptom.
Common Symptoms
- Rough or unstable idle
- Misfire under load
- Reduced throttle response and power
- Check engine light with misfire or lean codes
- Hesitation on cold start
How to Fix
Walnut-shell media blasting of the intake ports and valve faces, typically $300-$500 at a shop that does it routinely and $800-$1,200 at a dealer or specialist, repeated roughly every 60,000 miles. Chemical intake cleaners help only marginally once deposits are hard. The widely used preventive step is an oil catch can plumbed between the PCV valve and the intake manifold, fitted early in ownership. No recall or warranty extension covers this.
Sources for this issue (3)
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 Hyundai?
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 Hyundai it is documented across 5 models: Tucson, Elantra, Genesis, Santa Fe, Genesis Coupe.
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 Hyundai?
Published repair estimates on Hyundai range from $300 to $7,500 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.