P0304 on a Chevrolet Silverado 1500
P0304 means cylinder 4 Misfire Detected. On the Silverado 1500, a few causes come up far more than others.
What P0304 usually means on a Silverado 1500
P0304 pins the misfire to cylinder 4, which on the AFM 5.3L Silverado is one of the four deactivating cylinders. That makes a collapsed AFM lifter a leading suspect when cylinder 4 misfires hard and the engine ticks, as opposed to a simple coil or plug issue. On non-AFM engines the usual single-cylinder suspects apply. As with the other AFM cylinders, the branch point is whether a lifter tick accompanies the misfire.
Most common causes on the Silverado 1500
- Collapsed AFM lifter on cylinder 4 (5.3L)
Cylinder 4 is an AFM cylinder, so a hard misfire there with a tick strongly suggests a failed AFM lifter, an internal mechanical fault.
- Failed coil or worn spark plug on cylinder 4
The everyday single-cylinder cause. Swap the coil to test, and inspect the plug for wear or fouling.
- Oil-fouled plug from AFM oil consumption
Burnt oil on an AFM 5.3L can foul cylinder 4's plug, causing a misfire that returns unless consumption is addressed.
- Injector or compression problem on cylinder 4
A leaking injector or low compression, including a lobe damaged by a failed lifter, causes a misfire ignition parts cannot fix; confirm with a compression test.
What P0304 costs to fix on a Silverado 1500
A coil and plug for cylinder 4 is cheap; a collapsed AFM lifter is not, requiring intake and valvetrain teardown at a four-figure cost and an inspection of the cam lobe for that cylinder. Confirming whether this is a lifter or an ignition fault before disassembly is essential to avoid unnecessary work.
Fixing it
Check for a tick and test compression on cylinder 4 first. If ignition parts are good and the cylinder is an AFM cylinder ticking under load, plan for lifter replacement and inspect the camshaft.
For the full step-by-step diagnosis order (any vehicle), see the main P0304 guide.
Year, engine and mileage change the answer. Start a case and Redline weighs these causes against what your car shows, then names the check that would settle it.
Other codes on the Chevrolet Silverado 1500
Related symptoms
Chevrolet Silverado 1500 problems & recalls by year
Based on widely reported patterns for this model; individual causes vary by year, engine and history. Generic P0304 behavior is covered on the main P0304 page. Confirm with a scan tool before buying parts.
P0304 on your Silverado 1500?
Every problem becomes a Case. Tell Redline what your Silverado 1500 is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.