2021 Volvo XC90 T6 Cylinder 1 Misfire (P0301): Complete Diagnosis Guide

The 2021 Volvo XC90 T6's unique powertrain—combining turbocharging and supercharging in one 2.0L engine—delivers impressive power for a four-cylinder. When P0301 appears indicating cylinder 1 misfire, this sophisticated engine needs focused diagnosis to identify the failing component.

The T6 Engine's Unique Configuration

Volvo's T6 uses both a supercharger (for immediate low-RPM response) and a turbocharger (for high-RPM power). This complexity means more components that could potentially affect cylinder 1 operation, though the combustion fundamentals remain similar to simpler engines.

Cylinder 1 Location

In the XC90's inline-4 configuration, cylinder 1 is at the front of the engine, closest to the accessory drive. This position is relatively accessible for inspection and testing.

Symptoms of Cylinder 1 Misfire

• Rhythmic roughness at idle—consistent with single-cylinder pattern
• Check engine light on steady or flashing
• Noticeable vibration at stops
• Reduced power and acceleration
• Possible fuel smell from unburned mixture

Primary Causes

Ignition Coil Failure

Individual coil-on-plug ignition means cylinder 1 has its own dedicated coil that can fail independently.

Spark Plug Issues

The dual-boost environment (supercharger + turbo) creates high cylinder pressures that stress spark plugs significantly.

Fuel Injector Problems

Direct injection into the combustion chamber means any injector issue immediately affects that cylinder's performance.

Compression Loss

While less common on newer vehicles, valve or ring issues specifically affecting cylinder 1 can cause isolated misfires.

The Coil Swap Test

Swap cylinder 1's ignition coil with cylinder 2. Clear codes and drive. If the misfire moves (now P0302), the coil is confirmed bad. This simple test saves diagnostic time and parts cost.

Repair Costs