P0302 on 2012-2013 Kia Soul: Cylinder 2 Misfire Causes and Fixes

What's Unique About the 2012-2013 Kia Soul

The 2012-2013 Kia Soul was offered with two different four-cylinder engines: a 1.6L 'Gamma' GDI and a 2.0L 'Nu' MPI. While both can suffer from common ignition failures, the 1.6L GDI engine is known for developing carbon buildup on the intake valves over time. Because GDI engines inject fuel directly into the cylinder, there's no gasoline to wash and clean the valves, which can lead to airflow restriction and cause misfires that can be mistaken for a bad coil or plug. Furthermore, the 1.6L GDI was subject to a safety recall (NHTSA 19V120000) where a persistent misfire could lead to catalytic converter damage and, in severe cases, engine failure.

Symptoms You May Notice

• Check engine light is on (solid or flashing)
• Rough or shaking idle
• Engine hesitation or stumbling during acceleration
• Noticeable loss of power
• Reduced fuel economy
• Engine knocking noise in severe cases

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Ignition coils are a common wear item. While no specific recall exists for the 2012-2013 Soul, Kia issued a service action (SA321) for 2017-2018 Fortes with a similar 2.0L engine, instructing dealers to replace all four coils for any P030x misfire code, indicating a known weakness in this part family.
   How to confirm: Swap the ignition coil from cylinder 2 with another cylinder (e.g., cylinder 3). Clear the codes and drive the vehicle. If the code changes to P0303, the ignition coil is faulty and needs to be replaced. This is the most common and effective DIY diagnostic step. 🎬 See how to diagnose and fix common Kia misfire codes.
   Typical fix: Replace the ignition coil on cylinder 2. It is held on by a single 10mm bolt. 🎬 Watch: Step-by-step guide to replacing coils and spark plugs. Many owners choose to replace all four coils at once as a preventative measure, especially on higher mileage vehicles. A user on the r/KiaSoulClub subreddit fixed their P0302 at 172,000 miles by replacing all plugs and coils.
   Est. part cost: $25-$115
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug
   How to confirm: After ruling out the ignition coil, remove the spark plug from cylinder 2. Inspect it for wear (rounded electrode), fouling (black, oily, or white deposits), or an incorrect gap. Oil on the plug threads could indicate a leaking valve cover gasket.
   Typical fix: Replace the spark plug in cylinder 2. It is highly recommended to replace all four spark plugs at the same time with the correct OEM-spec type to ensure consistent performance and prevent future misfires.
   Est. part cost: $15-$25 per plug
3. Intake Valve Carbon Buildup (1.6L GDI Engine) 🟡 Medium Probability The 1.6L GDI engine injects fuel directly into the cylinder, so gasoline and its detergents never wash over the intake valves. Oil vapor from the PCV system can bake onto the hot valves, restricting airflow and causing misfires, especially at idle or low RPMs.
   How to confirm: This is difficult to confirm without some disassembly. After ruling out ignition and fuel injector issues, a borescope can be used to visually inspect the intake valves by removing the intake manifold. A compression or leak-down test may also point to a valve sealing issue.
   Typical fix: The intake valves need to be physically cleaned. The most effective method is walnut shell blasting, a professional service. Some chemical intake cleaning sprays (often called 'induction cleaning') may provide temporary or partial improvement.
   Est. part cost: $20-$40 for DIY cleaning kits, $400-$700+ for professional walnut blasting service.
🎬 Watch: The ultimate DIY guide to cleaning GDI intake valves.
4. Clogged or Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: After ruling out ignition issues, you can swap the fuel injector from cylinder 2 with another cylinder, though this is more involved than a coil swap. A Hyundai technician on Reddit noted that leaking injectors are common on these engines and can be diagnosed by monitoring fuel pressure after shutdown; a dropping pressure indicates a leak.
   Typical fix: Replace the faulty fuel injector. It's often recommended to replace the set if the vehicle has high mileage.
   Est. part cost: $50-$150

Rare But Worth Checking

• Low Engine Compression: If ignition and fuel system checks don't find the issue, a mechanical problem could be the cause. This can stem from worn piston rings, a burnt valve, or even catastrophic engine damage related to recall 19V120000 on the 1.6L GDI. A compression test is needed to diagnose this. NHTSA ODI #11725093 describes a case where a vehicle stalled with codes P0300, P0304, and P0302, showing no pressure in cylinders 2 and 4.
• Vacuum Leak: A leak in a vacuum hose or the intake manifold gasket can introduce unmetered air, leaning out the air/fuel mixture and causing a misfire. This would typically affect more than one cylinder and may be accompanied by a P0171 (System Too Lean) code.
• Leaking Valve Cover Gasket: → Shop Engine Valve Cover A hardened or cracked valve cover gasket can allow engine oil to leak into the spark plug tubes. This oil can saturate the ignition coil boot and foul the spark plug, causing a misfire specific to that cylinder. When removing the coil, check for oil in the spark plug well.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner. Confirm P0302 is present and note any other codes, like P0300.
2. Identify cylinder 2. On these transverse engines, the cylinders are numbered 1-2-3-4, starting from the passenger side (belt side) and moving toward the driver's side (transmission side). Cylinder 2 is the second from the passenger side.
3. Swap the ignition coil from cylinder 2 with the coil from cylinder 3. Clear the codes with the scanner.
4. Drive the vehicle until the check engine light returns. If the code is now P0303, the ignition coil is the problem.
5. If the code remains P0302, the coil is likely good. Put the coils back in their original positions. Now, swap the spark plug from cylinder 2 with the plug from cylinder 3. Clear codes and re-test.
6. If the code is still P0302, the issue is likely not a simple ignition component. The next steps involve checking the fuel injector, wiring, and for carbon buildup (especially on the 1.6L GDI).
7. If all else fails, perform a compression test to check for mechanical engine problems like a bad valve or piston rings.

Parts You'll Likely Need

• Ignition Coil (1.6L Engine) (OEM #27301-2B100) — This is the most frequent cause of a single-cylinder misfire on this engine. This part is also used on the Hyundai Accent and Veloster.
  Trusted brands: Kia/Hyundai (OEM), NGK (P/N 49055), Delphi (P/N GN10634), Denso (P/N DIC-0207)
  OEM price range: $75-$115
  Aftermarket price range: $25-$70
• Ignition Coil (2.0L Engine) (OEM #27300-2E000) — This is the most frequent cause of a single-cylinder misfire on this engine. This part is shared with the Kia Forte and Hyundai Elantra.
  Trusted brands: Kia/Hyundai (OEM), NGK, Delphi, Bremi
  OEM price range: $55-$100
  Aftermarket price range: $30-$80
• Spark Plug (1.6L Engine) (OEM #18846-10060) — A worn or fouled spark plug is the second most common cause of a misfire after the ignition coil.
  Trusted brands: Kia (OEM), NGK, Bosch
  OEM price range: $20-$30
  Aftermarket price range: $8-$18
• Spark Plug (2.0L Engine, Iridium) (OEM #18846-11060) — A worn or fouled spark plug is the second most common cause of a misfire. The 2.0L engine typically uses longer-lasting iridium plugs.
  Trusted brands: Kia (OEM), NGK, Bosch
  OEM price range: $17-$24
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• P0300 — If the misfire is severe or intermittent, or if other cylinders begin to misfire, a P0300 (Random/Multiple Cylinder Misfire) code may be set alongside P0302.
• P0301, P0303, P0304 — These codes indicate misfires in other cylinders. If they appear with P0302, it points towards a systemic issue like multiple failing coils, worn spark plugs across all cylinders, a vacuum leak, or significant carbon buildup.

Technical Service Bulletins (TSBs) & Recalls

• TSB SA321: While for later 2017-2018 Kia Fortes with the 2.0L MPI engine, this service action is relevant as it shows a pattern of premature ignition coil failure from the manufacturer, instructing dealers to replace all four coils if any misfire code is present.
• TSB SA285: Also for 2017 Fortes, this TSB involved an ECU logic update to prevent the computer from being overly sensitive and falsely detecting misfires. This indicates that sometimes the code can be a software issue, not a hardware failure.

Platform-Specific Known Issues

• Recall 19V120000 (Kia SC176) was issued for 2012-2016 Souls with the 1.6L GDI engine. The recall addresses a condition where high exhaust temperatures, often caused by a persistent misfire like P0302, can damage the catalytic converter. This damage can lead to particles entering the engine, causing piston damage and potential engine failure. The remedy involves an ECU update to better protect the catalyst, and replacement of the converter

Mechanic-Grade Diagnostic Values

• Ignition Coil Secondary Resistance (1.6L GDI) — expected: ~6.0 kΩ (6000 ohms). Failure: Significant deviation from this value, or an open/infinite reading.
• High-Pressure Fuel System (1.6L GDI) — expected: 2,000 to 2,800 PSI. Failure: Pressure that is significantly below this range under load may indicate a failing high-pressure fuel pump (HPFP).
• Misfire Detection Threshold — expected: The ECM will set code P0302 if the misfire rate on cylinder 2 exceeds 2% over a 1,000 revolution count.. Failure: This is the trigger condition itself, viewable by monitoring misfire counts in Mode 6 or with a capable scan tool.
• Fuel Injector Electrical Connector — expected: 2-pin blade style connector.. Failure: Corrosion or damage to the pins or locking tab. The connector itself is available as a replacement part.

Hidden / Shadow Codes Worth Checking

• Mode 6, Test ID $A2-$A7: OBD-II Mode 6 provides access to non-continuous monitor test results. For misfires, Test IDs $A2 through $A7 (for a 4-cyl) will typically store the raw misfire count for each cylinder for the current and last 10 driving cycles. This allows a technician to see if cylinder 2 has a significantly higher count than others, even before the count crosses the threshold to set a P0302. (see via A professional scan tool or an advanced consumer OBD-II app that can display Mode 6 data.)

Scan Tool Commands That Help

• Kia GDS (Global Diagnostic System): Actuation Test — After ruling out spark, a technician can use the GDS to command the fuel injector on cylinder 2 to open and close (click), verifying the wiring and injector solenoid are functioning without having to remove the injector.
• Kia GDS (Global Diagnostic System): Live Data / DTC Guide — The GDS provides dealer-level live data, such as individual cylinder misfire counters and fuel trim adjustments. It also contains a specific diagnostic procedure guide for each fault code, walking the technician through a logical test plan.
• Kia GDS (Global Diagnostic System): ECU Programming / Initialization — If diagnosis leads to a faulty Engine Control Module (ECM), a replacement ECM must be programmed and initialized to the vehicle's VIN and immobilizer system using the GDS. A generic scanner cannot perform this function.

Wiring & Ground Locations

• Ignition Coil Connector — Connects directly to the top of each ignition coil, located on the valve cover.. The plastic locking tabs can become brittle and break, leading to a poor connection. The connector and its pigtail wiring can also be damaged by heat and vibration, causing an intermittent misfire. This connector is sold as a separate part for repair.
• ECM Ground — The Engine Control Module (ECM) has multiple ground pins that connect to chassis ground. On a schematic, these are shown connecting from the ECM directly to a ground symbol.. A poor ground connection for the ECM or the ignition coil driver circuit can cause a wide range of issues, including weak spark or erratic injector behavior. Verifying clean, tight ground connections is a critical step in advanced diagnosis.

Real Owner Repair Stories

• YouTube comment (Not specified, but symptoms align with P0302.) — Bad rough idle, engine shaking, and stalling.
  ❌ Tried (didn't work) Replacing ignition coils, Replacing spark plugs
  ✅ What actually fixed it The user suspected a clogged fuel injector and added Redline fuel injector cleaner to the fuel tank, which resolved the misfire code and symptoms.
• Reddit user -Potato-Chip- (Kia with 1.6L GDI engine (similar to 2012-2013 Soul)) — P0300, P0303, and P0304 codes (misfires on multiple cylinders).
  ❌ Tried (didn't work) Initial diagnosis pointed towards common ignition or fuel issues.
  ✅ What actually fixed it The root cause was a burnt exhaust valve in cylinder #3, which required mechanical engine repair. This highlights that persistent misfire codes can indicate a serious internal engine problem.

Documented NHTSA Reports

• An owner reported in NHTSA ODI #11720416 that after a failure recurred, a code reader retrieved DTCs P0017, P0301, P0302, P0303, and P0304.
• According to NHTSA ODI #11650213, an engine began making horrible noises and lost power, producing codes for multiple misfires and individual cylinder misfires including P0300, P0301, P0302, and P0303.
• NHTSA ODI #11699918 describes a situation involving extensive internal engine damage requiring a full engine replacement, with diagnostic trouble codes including P0300, P0302, P0303, and P0326.
• In NHTSA ODI #11700997, an owner documented expenses for a fuel system cleaning and spark plug replacement/tune-up after receiving engine diagnostic codes P0302 and P0300.

"I Checked Everything" — The Actual Cause

• A common diagnostic step for misfires is a smoke test to find vacuum leaks. However, on the 1.6L GDI engine, a smoke test can come back clean while a significant airflow problem still exists. This occurs when carbon buildup forms on the back of the intake valves, restricting airflow into the cylinder. This is a restriction, not a leak, so a smoke test will not detect it. The actual cause is the carbon buildup, which requires physical cleaning (like walnut blasting) to resolve, a procedure that is often overlooked until all other options are exhausted.

OEM Part Supersession History

• 35320-2B100 → 35320-2B140 — Part revision for the 1.6L GDI high-pressure fuel pump.
• 27301-2A000 (Older, similar design) → N/A - Incompatible — This is not a direct supersession but a known point of confusion. The correct part for the 2012-2013 1.6L GDI is 27301-2B100.
  Heads up: The older 27301-2A000 coil may have the same physical shape but features a different internal pin layout in the connector, making it electrically incompatible with the 2012+ models. Using this part will result in a no-spark condition.

Model Year Variations Within This Range

• 2012-2013: The 2012 model year marked a significant powertrain update. The base 1.6L engine was upgraded to a Gasoline Direct Injection (GDI) 'Gamma' unit, boosting power to 138 hp. The optional 2.0L 'Nu' engine's power increased to 164 hp. Both engines were paired with new 6-speed automatic or manual transmissions, replacing the previous 4- and 5-speed units. The introduction of the 1.6L GDI engine is the most critical variation for P0302, as it introduces the specific problem of carbon buildup on intake valves not seen on the 2.0L MPI engine.

Diagnostic Flowchart

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0300 — Random/Multiple Cylinder Misfire Detected. Often appears alongside P0302 if multiple ignition coils are failing (as noted in TSB SA321) or if there is widespread carbon buildup on the 1.6L GDI engine.
• P0301 — Cylinder 1 Misfire Detected. A related misfire code that can appear concurrently with P0302 if multiple ignition coils fail simultaneously, as seen in owner reports.
• P0303 — Cylinder 3 Misfire Detected. This code will appear during the diagnostic process if you swap a faulty ignition coil or spark plug from cylinder 2 to cylinder 3 to confirm the component failure.
• P0420 — Catalyst System Efficiency Below Threshold (Bank 1). Directly related due to Recall 19V120000 (SC176), where a persistent P0302 misfire causes high exhaust temperatures that damage the catalytic converter.

Frequently Asked Questions