The P0304 code in your 2021 Kia Telluride indicates the engine control module has detected persistent misfires in cylinder 4. The three-row SUV's 3.8L V6 requires understanding of V6 cylinder configuration for effective diagnosis and repair of this combustion problem.
Understanding P0304 in the 2021 Telluride
The 2021 Telluride features the 3.8L Lambda II V6 producing 291 horsepower through variable valve timing and direct fuel injection. This transverse-mounted V6 positions cylinder 4 on the rear bank toward the firewall. Kia's engine management identifies the specific misfiring cylinder through crankshaft velocity pattern analysis.
V6 Misfire Causes
The naturally aspirated V6 faces standard ignition wear patterns. Spark plug electrode erosion occurs through normal operation. Ignition coils degrade from repeated heat cycling. Direct injection creates conditions for carbon buildup on intake valves over time. The rear bank location makes cylinder 4 less accessible but subjects it to specific thermal conditions.
Diagnostic Approach
Retrieve all codes and analyze freeze frame data. Access the rear bank for cylinder 4 inspection—the transverse mounting positions this bank toward the firewall. Test ignition coil output and spark plug condition. Verify fuel injector operation. Consider carbon buildup for higher-mileage vehicles.
Repair Solutions
Install Kia-specified spark plugs for the 3.8L V6. Replace ignition coils testing outside specifications. Address fuel system concerns. Professional carbon cleaning benefits vehicles showing intake valve deposit symptoms.