P0305 Chevy Silverado: Cylinder 5 Misfire Diagnosis and Fix

P0305 on a Chevy Silverado indicates a confirmed misfire in cylinder 5 — the third cylinder from the front on the driver’s side of the engine. The diagnosis process mirrors P0304 closely, just targeting the driver-side bank instead.

Watch a cylinder-specific misfire traced to a failed ignition coil — the same plug, spark and coil checks apply to P0305.

What P0305 Means

The ECM detects misfire events by monitoring crankshaft deceleration — each misfire causes a tiny but measurable dip in crank speed as that cylinder fails to fire. P0305 specifically means cylinder 5 misfired enough times to cross the detection threshold. It can appear alone or alongside P0300 (random misfire) if the cylinder 5 misfire is severe enough to cause broader engine roughness.

Cylinder 5 Location

On all GM V8 engines: Driver’s side front-to-rear = cylinders 1, 3, 5, 7. Cylinder 5 is the third cylinder from the front on the driver’s side. This is the rear AFM cylinder on the driver’s bank on AFM-equipped 5.3L trucks — an important detail for diagnosis.

Common Causes of P0305

Same as all single-cylinder misfire codes: failed ignition coil on cylinder 5, worn or fouled spark plug, defective fuel injector, cracked coil boot, or on 2007–2021 5.3L trucks — a failed AFM lifter. Cylinder 5 is an AFM deactivation cylinder on the GM 5.3L, making lifter failure a specific risk. Additionally, on trucks with a collapsed engine mount, cylinder 5’s coil can develop a poor connection due to physical engine movement — worth checking if mounts are worn.

Quick Diagnosis Steps

Swap the ignition coil from cylinder 5 to a known-good cylinder (e.g., cylinder 1). If misfire moves to cylinder 1, replace the cylinder 5 coil. If misfire stays on cylinder 5, move to spark plug inspection. Replace the cylinder 5 plug if it shows wear, fouling, or damage. If coil and plug are good, use a scan tool to monitor fuel trim on the driver’s bank — a lean condition on bank 1 (driver’s side) can cause P0305 even with good ignition components.

Related Codes

P0305 often appears with P0300 (random misfire) when the misfire is severe. On AFM trucks, P0305 combined with an oil consumption complaint and no response to coil/plug diagnosis strongly suggests AFM lifter failure — see AFM delete guide. Also see: P0304 cylinder 4 misfire and P0300 random misfire.