P0303 on 2020-2025 Kia Telluride: Cylinder 3 Misfire Causes and Fixes

What's Unique About the 2020-2025 Kia Telluride

The Kia Telluride's Lambda II 3.8L is a Gasoline Direct Injection (GDI) engine. While generally robust, some Kia engines, including related platforms, have been noted for potential oil consumption issues as detailed in TSB ENG222. An owner complaint for a 2020 Telluride specifically links excessive oil consumption to fouled spark plugs, causing multiple misfire codes including P0303. This means that while standard ignition component failure is common, a fouled spark plug on this engine could be a symptom of a more significant underlying issue with piston rings, which is a known problem on some Kia engines.

Symptoms You May Notice

• Rough or shaky idle
• Hesitation or stumbling during acceleration
• Reduced engine power
• Flashing or solid Check Engine Light
• Decreased fuel economy
• A smell of raw fuel from the exhaust
• Vehicle jerks or stalls

Most Likely Causes

1. Failed Ignition Coil 🔴 High Probability Coil-on-plug ignition systems are common failure points on many modern engines due to constant heat and vibration. The coil for cylinder 3 is located on the rear bank of the V6 (against the firewall), which can experience higher temperatures, potentially leading to premature failure. A Reddit user with a 2021 Telluride reported a P0304 (cylinder 4) misfire caused by a broken coil.
   How to confirm: Swap the ignition coil from cylinder 3 with another cylinder (e.g., cylinder 1 on the same bank or cylinder 4 on the front bank). Clear the codes and drive the vehicle. If the code changes to P0301 or P0304, the ignition coil is faulty.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace all coils on the same bank, or all six, if they are original and the vehicle has high mileage.
   Est. part cost: $75-$110 per coil (OEM)
2. Worn or Fouled Spark Plug 🔴 High Probability
   How to confirm: Remove the spark plug from cylinder 3 and inspect it. Look for a worn electrode, cracks in the porcelain, or heavy carbon/oil deposits. Oil fouling is a key indicator of potential oil consumption issues related to TSB ENG222. A Reddit user with a 2022 Telluride at only 27,500 miles experienced a misfire diagnosed as a potential spark plug issue.
   Typical fix: Replace the spark plug. It is best practice to replace all six spark plugs at the same time, ensuring they are gapped correctly.
   Est. part cost: $15-$30 per plug
3. Clogged or Faulty Fuel Injector 🟡 Medium Probability Gasoline Direct Injection (GDI) injectors operate under extremely high pressure and can be susceptible to clogging from fuel deposits or contaminants over time.
   How to confirm: This is more difficult for a DIYer. A professional can perform a fuel injector balance test. A simpler, though less definitive, method is to swap the injector with another cylinder to see if the misfire code follows.
   Typical fix: Professionally clean or replace the faulty fuel injector. It's often recommended to replace all injectors on the same fuel rail if one fails.
   Est. part cost: $60-$100 per injector

Rare But Worth Checking

• Internal Engine Damage (Piston Rings, Burnt Valve): NHTSA complaints on Kia vehicles with similar engines have cited P0303 in conjunction with severe internal issues like bad piston rings causing oil consumption (ODI #11717327) or burnt valves (ODI #11697208). This is a worst-case scenario, often requiring major engine repair or replacement. A Reddit user with a 2021 Telluride reported losing 6 quarts of oil between changes, which led to a cylinder 5 misfire, indicating how oil loss can damage components.
• Vacuum Leak: A vacuum leak from a cracked hose or a failed intake manifold gasket near cylinder 3 can introduce unmetered air, leading to a lean misfire. This is less common for a single-cylinder misfire but is possible, especially if accompanied by a P0300 code.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner and confirm P0303 is present. Note any other codes.
2. Check the freeze frame data to understand the engine conditions (speed, load, temperature) when the misfire occurred.
3. Locate cylinder 3. On the Telluride's transverse-mounted 3.8L V6, the rear bank (closest to the firewall) contains cylinders 1, 3, and 5, from passenger to driver side. The front bank contains 2, 4, and 6. Cylinder 3 is the middle cylinder on the rear bank.
4. Swap the ignition coil from cylinder 3 with an easily accessible cylinder on the front bank (e.g., cylinder 4). Clear the codes, run the engine, and see if the misfire code moves to P0304. If it does, the coil is bad.
5. If the code remains P0303, swap the spark plug from cylinder 3 with the one from the cylinder you just used for the coil test. Clear codes and re-test. If the code moves, the spark plug is bad.
6. When you remove the spark plug, inspect it closely. Heavy, black, oily deposits are a strong indicator of oil consumption, which may be related to TSB ENG222. This is a critical diagnostic clue.
7. If the coil and plug are good, inspect the wiring and connector for the cylinder 3 coil and fuel injector for any damage, looseness, or corrosion.
8. If the above steps do not identify the issue, the problem is likely a fuel injector or a more serious mechanical engine issue. At this point, professional diagnosis is recommended, which may include a fuel injector balance test, a compression test, or a leak-down test to check for internal engine problems.

Parts You'll Likely Need

• Ignition Coil (OEM #27310-3L000) — This is one of the most common failure points for a single-cylinder misfire. Heat and vibration cause the coil to fail over time. This part number fits the Telluride and other Kia/Hyundai models with V6 engines.
  Trusted brands: Kia (OEM), Denso, NGK
  OEM price range: $75-$110
  Aftermarket price range: $40-$80
• Spark Plug (OEM #18869-01100) — Spark plugs are a routine maintenance item and can become worn or fouled, especially if oil consumption is an issue.
  Trusted brands: NGK, Denso
  OEM price range: $20-$35
  Aftermarket price range: $15-$25

Related Codes That Often Appear With This One

• P0300 — If the condition causing the misfire is not isolated to one cylinder (e.g., bad fuel, vacuum leak, systemic oil consumption), a P0300 (Random/Multiple Cylinder Misfire) code may appear alongside P0303.
• P0301, P0302, P0304, P0305, P0306 — Other specific cylinder misfire codes may appear with P0303 if multiple cylinders are affected, as seen in NHTSA complaint #11717327 where oil consumption fouled plugs on several cylinders.

Technical Service Bulletins (TSBs) & Recalls

• ENG222 (Multiple Revisions, latest is TSB_ENG222_R8): 'Excessive Oil Consumption - Nu/Gamma/Theta/Kappa Engines' - This TSB details the official Kia procedure for diagnosing and confirming excessive oil consumption, which can be a root cause of spark plug fouling that leads to a P0303 code. The procedure involves an oil consumption test over 1,000 miles and potentially a combustion chamber cleaning process.

Platform-Specific Known Issues

• A notable issue cited in NHTSA complaint #11717327 for a 2020 Telluride is excessive oil consumption due to piston rings, leading to fouled spark plugs and multiple misfire codes, including P0303. This is covered under Kia's Technical Service Bulletin ENG222, which outlines an oil consumption test procedure. If a vehicle fails this test (consuming over 1 quart per 1,000 miles), Kia may authorize engine repairs or replacement. Several revisions of this TSB exist, with the latest being ENG222_R8 as of April 2025.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: ~1.0 ohms. Failure: A reading that is significantly higher (open) or lower (short) than the specification.
• Ignition Coil Connector Contact Resistance — expected: < 5mΩ (milliohms). Failure: Higher resistance indicates a poor connection, which can cause intermittent misfires.
• Mode $06 Misfire Counts — expected: Zero or very low counts per cylinder during a drive cycle.. Failure: A high number of misfire counts logged for cylinder 3, even without a pending or active P0303 code, indicates an intermittent issue.

Scan Tool Commands That Help

• Kia GDS (Global Diagnostic System): Cylinder Power Balance Test — This function allows a technician to disable one cylinder at a time (by cutting fuel or spark) and observe the corresponding drop in engine RPM. If disabling cylinder 3 results in little or no RPM drop compared to other cylinders, it confirms that cylinder 3 is not contributing power, helping to isolate the fault.
• Kia GDS (Global Diagnostic System): Actuation Test — Can be used to command the fuel injector for cylinder 3 to open and close. The technician can listen for an audible click to verify the injector is mechanically responding to the ECM's command.
• Advanced OBD-II Scanner: View Mode $06 Data — To check for intermittent misfires that haven't yet triggered a P0303 code. The ECM tracks misfire events for each cylinder, and this data can reveal a problem with cylinder 3 before it becomes a constant fault.

Wiring & Ground Locations

• Ignition Coil Connector (Cylinder 3) — On the ignition coil for cylinder 3, which is the middle cylinder on the rear bank of the engine, closest to the firewall.. The 4-pin connector provides power, ground, and the trigger signal from the ECM. A loose, corroded, or damaged connector or wiring can directly cause a P0303 by interrupting the signal or power to the coil. The connector is typically a 4-pin oval shape with blade-style terminals.

Real Owner Repair Stories

• Reddit r/KiaTelluride user (2020 Kia Telluride, 128,000 miles) — Misfire in Cylinder 6, then after repair, misfires in Cylinders 5 & 6 plus a heater control circuit code.
  ❌ Tried (didn't work) Initial replacement of coils and plugs on cylinder 6.
  ✅ What actually fixed it The user discovered oil on the spark plug threads for cylinders 5 and 6, indicating a leaking valve cover gasket. The implied fix is the replacement of the valve cover gasket to stop oil from fouling the plugs and coils, which was the root cause of the recurring misfires.

OEM Part Supersession History

• Unknown → 27310-3L000 — This is the current OEM part number for the ignition coil for the rear bank (cylinders 1, 3, 5).
  Heads up: The front bank (cylinders 2, 4, 6) uses a different part number, 27310-3L030. While they may appear similar, they are not interchangeable.

Model Year Variations Within This Range

• 2023-2025: The Kia Telluride received a facelift for the 2023 model year, which included revised exterior styling and significant interior updates like a new dual-screen dashboard. However, the core powertrain, the Lambda II 3.8L GDI V6 engine and 8-speed automatic transmission, remained unchanged from the 2020-2022 models. Therefore, the causes and diagnostic procedures for a P0303 code are identical across the 2020-2025 year range.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Spontaneously Cracking Windshields 🟠 Medium — Widespread complaints across 2020-2023 model years. Can occur without impact. A class-action lawsuit has been filed regarding this issue. (Ref: Customer Satisfaction Initiative for 2020 models, but no formal recall.)
• Tow Hitch Wiring Harness Fire Risk 🔴 High — Affects 2020-2022 models equipped with the genuine Kia 4-pin tow hitch harness. Can cause a fire even when the vehicle is parked and off. (Ref: NHTSA Recall 22V-626 (Kia Campaign SC247))
• Excessive Engine Oil Consumption 🔴 High — Reported across multiple model years. Can lead to engine damage if not monitored. Considered excessive if over 1 quart per 1,000 miles. (Ref: TSB ENG222 (multiple revisions))
• Blank or Glitching Instrument Cluster/Infotainment Screen 🟡 Low — Common complaint where the digital dash or center screen goes blank or reboots randomly, temporarily losing access to speedometer and vehicle info. (Ref: Kia issued a voluntary recall/software update for some 2022 and 2023 models to fix this.)
• Harsh Shifting or Transmission Hesitation 🟠 Medium — Owners report jerky shifting, lurching, or delays when shifting from Park to Drive, particularly when the vehicle is cold.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For a simple ignition coil replacement, a used OEM part from a low-mileage donor vehicle can be a cost-effective option. Since it's an external, easily accessible part (on the front bank, at least), its condition is easy to inspect.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Check for cracks or damage to the plastic housing and rubber boot.
• Ensure the electrical connector pins are clean, straight, and free of corrosion.
• Avoid parts from engines that show signs of heavy oil leaks or overheating.
• If possible, verify the donor vehicle did not have misfire-related trouble codes.

OEM-only on this vehicle (don't cheap out):

• Fuel Injectors: GDI injectors are high-precision components. Aftermarket quality can be inconsistent, and a faulty injector can lead to serious engine damage. OEM or a reputable OE supplier like Bosch is recommended.
• Engine Sensors (Crank/Cam): The timing of the engine is critical. Cheaper aftermarket sensors have a higher failure rate and can cause difficult-to-diagnose running issues. Stick with OEM or a trusted brand like Denso.

Aftermarket brands forum-validated for this vehicle:

• Ignition Coils: NGK and Denso are highly reputable OE suppliers and are considered safe, high-quality alternatives to dealer OEM parts.
• Spark Plugs: NGK and Denso are the standard recommendations and often the original equipment manufacturer.

Brands owners have reported issues with on this vehicle:

• Unbranded/white-box ignition coils and sensors from online marketplaces. These parts often have a high failure rate and may not meet OEM specifications, leading to repeat repairs.

Real Owner Stories

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

Related OBD-II Codes

• P0301 — Misfire code for cylinder 1, located on the same rear bank as cylinder 3.
• P0305 — Misfire code for cylinder 5, located on the same rear bank as cylinder 3; often triggered by the same oil consumption issues described in TSB ENG222.
• P0304 — Misfire code for cylinder 4; used as a comparison cylinder during diagnostic coil-swapping procedures.
• P0300 — Random or multiple cylinder misfire code that may appear alongside P0303 if oil fouling affects multiple plugs.

Frequently Asked Questions