P0307 on a Chevrolet Silverado 1500

What P0307 usually means on a Silverado 1500

P0307 flags a misfire on cylinder 7, the last of the four AFM-deactivating cylinders on the 5.3L V8. A hard misfire on cylinder 7 accompanied by a ticking noise is a classic collapsed-AFM-lifter presentation, which is why these trucks so often show misfire codes on cylinders 1, 4, 6, and 7. Without a tick, or on non-AFM engines, the usual coil, plug, and injector suspects apply. Recognizing cylinder 7 as an AFM cylinder is central to diagnosing it correctly.

Most likely causes on this model

1. Collapsed AFM lifter on cylinder 7 (5.3L)

   Cylinder 7 deactivates under AFM, so a hard misfire there with a tick strongly implicates a failed AFM lifter rather than an ignition part.

2. Failed coil or worn spark plug on cylinder 7

   The standard single-cylinder cause. Swap-test the coil and inspect the plug for wear or oil fouling.

3. Oil-fouled plug from AFM oil consumption

   Burnt oil on an AFM 5.3L can foul cylinder 7's plug, misfiring until the consumption is addressed.

4. Injector or compression issue on cylinder 7

   A leaking injector or low compression, including from a lifter-scored cam lobe, causes a misfire ignition parts will not fix; verify with compression testing.

What it costs on a Silverado 1500

A coil and plug for cylinder 7 is a low-cost repair; a collapsed AFM lifter is a major, four-figure valvetrain job that should include inspecting the cam lobe for that cylinder. Confirming lifter versus ignition before teardown is again the key to controlling cost.

Fixing it

Check for a tick and test compression on cylinder 7 first. If ignition parts are good and the cylinder is an AFM cylinder with a tick, plan for lifter replacement and inspect the camshaft.

For the full step-by-step diagnosis order (any vehicle), see the main P0307 guide.

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