P0302 on Chevrolet

The 5.3L V8 with Active Fuel Management (AFM/cylinder deactivation) is prone to two linked failures: excessive oil consumption from worn piston rings and an AFM oil deflector that sprays oil at the cylinder walls, and collapsed/failed AFM lifters that can damage the camshaft. Burning oil fouls spark plugs and can trip low-oil shutdown commands; a failed lifter causes a ticking/knocking misfire. GM settled the Siqueiros class action ($150M) over the LC9 5.3L piston-ring defect for 2011-2014 vehicles built on/after Feb 10, 2011.

A well-documented problem on the Atlas inline-five engines is dropped or loosened valve seats in the cylinder head, often after overheating or repeated thermal cycling. Owners report sudden misfires, rough running, low compression, flashing MIL, and in some cases complete loss of power. This issue appears in owner forums, repair discussions, and NHTSA complaints, and typically requires cylinder head replacement or machine work rather than simple ignition parts.

Because the 1.5L turbo (and the earlier 2.4L SIDI) is a gasoline direct-injection engine, no fuel washes over the back of the intake valves. Over 40k-80k miles, oil vapor from the PCV system bakes onto the valves as hard carbon, restricting airflow and disrupting the seal. Owners report a check-engine light with single- or multi-cylinder misfires that are worst on a cold start, plus a slight loss of power and rougher idle. GM technical document PIP5029E acknowledges misfires caused by 'major carbon build up on the intake and/or exhaust valves.'

The direct-injection fuel injectors on the 1.5L turbo can leak - internally past a cracked injector body/tip (dumping raw fuel into the cylinder and causing a misfire) or externally past worn upper O-rings (fuel smell, weeping at the rail). This is distinct from the covered high-pressure fuel-pump and in-tank fuel-pump-module failures. GM issued a Customer Satisfaction Program for a fuel-injector leak on some 2025 Equinox that directs dealers to replace all four injectors and the fuel feed pipe.

P0302 on the Malibu is most often a failing ignition coil or a worn/fouled spark plug at cylinder 2. On the four-cylinder Ecotec engines (2.2L, 2.4L, 2.5L) each cylinder has its own coil, so when the #2 coil weakens it can no longer produce a strong enough spark and that cylinder misfires. A carbon-fouled, worn, or wrong-gap plug at #2 does the same. Because oil consumption on the 2.4L can foul plugs prematurely, a repeat P0302 there can point back to that engine's oil-burning tendency. A flashing check-engine light with this code means raw fuel is reaching the catalytic converter and driving should stop.

The 1996+ 4.3L Vortec V6 uses a Central Sequential Fuel Injection (CSFI) 'spider' assembly under the upper intake plenum: a central injector body with flexible nylon tubes feeding poppet-valve nozzles at each intake port. Residual fuel bakes into varnish on the ball-to-seat face, so the poppets clog and, more importantly, lose their ability to seal, leaking fuel into the intake and opening at the wrong pressure. This is one of the most-documented S-10 4.3L driveability faults. GM issued warranty extension 99066F (to 10yr/200k mi) covering the poppet spray nozzles on 1996-2003 CSFI systems, confirming its prevalence.

The 5.3L (and 6.2L) V8 with Active Fuel Management — GM's cylinder-deactivation system that drops the engine to 4 cylinders to save fuel — is notorious for collapsed AFM lifters. The special deactivating lifters (and the lifter oil-manifold/VLOM that feeds them) fail when oil pressure/timing to the lifter is compromised, causing the lifter roller to seize. A collapsed lifter no longer opens its valve, producing a dead-cylinder misfire, a loud ticking/tapping, rough idle and major power loss. If driven on, a collapsed lifter can wipe the camshaft lobe and destroy the cam, turning a lifter job into a top-end rebuild. This is consistently ranked the #1 Silverado engine problem and generates heavy forum and search traffic across the entire 2007-2019 AFM era. Disabling AFM (range tuner/AFM delete) is the common owner mitigation.

The turbocharged 2.7L inline-4 (RPO L3B, marketed as TurboMax) used in fourth-gen Silverado 1500 work-grade and mid-trim trucks has generated a growing body of owner complaints distinct from the better-known 5.3L/6.2L V8 problems. Reported failures include collapsed/failed valve lifters (some at very low mileage — one documented 2022 Silverado Custom failed at ~22k miles), heavy carbon accumulation on the direct-injection intake valves causing rough idle, hesitation and 'chugging' under load, sticking PCV valves, and elevated oil consumption (owners report roughly a quart every 1,000-1,500 miles). Because the 2.7L is heavier-loaded in the full-size Silverado than in the Colorado/Canyon, it spends more time under boost and heat, which owners and shops link to accelerated valvetrain and turbo wear. GM issued repair campaigns in 2024 touching L3B/L2R engines.

The Central Sequential/Port Fuel Injection ('spider') assembly used on Vortec 4.3L/5.0L/5.7L engines feeds nylon lines to poppet or MPFI nozzles inside the intake. Over time the poppet valves gum up and stick, O-rings and the pressure regulator leak, and the nylon lines crack. The result is misfires, hard starting, rough idle, a noticeable drop in fuel economy, and often a raw-fuel/rich condition. A leaking regulator can even flood a cylinder (hydrolock risk). Very high-demand failure on these older trucks.

The fuel injector wiring harness on the Duramax diesel routes across the top of the engine under the valve covers. The harness rubs against the valve cover and rocker arms, causing the insulation to wear through and the wires to short or open. When an injector wire is damaged, the affected cylinder misfires, the engine runs rough, and white smoke pours from the exhaust. The chafing is accelerated by engine vibration and can affect multiple cylinders over time. GM released updated harness routing clips but the fundamental design has the harness in a high-wear location.

The 1.8L is prone to ignition coil (cassette-style coil pack) and spark plug degradation that causes random and single-cylinder misfires, rough idle, and hesitation. A frequent aggravating factor is oil pooling in the spark plug wells/tubes from a leaking valve cover gasket, which fouls the plugs/coils and re-triggers misfires until the gasket is addressed. This valve-cover-gasket-into-spark-plug-tube leak is a well-documented failure pattern on this engine.

The 1.4L engine in the Spark is prone to premature ignition coil failure, often causing misfires and rough running. Individual coil packs fail due to heat soak in the tight engine bay. Spark plugs also wear faster than the recommended interval suggests.

The Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) systems on the 5.3L and 6.2L V8 engines deactivate cylinders to save fuel by collapsing hydraulic valve lifters. These lifters have a complex locking pin mechanism that fails, causing the lifter to collapse and the affected cylinder to misfire. A collapsed lifter can also damage the camshaft lobe it rides on, turning a $300 lifter into a $3,000 camshaft and lifter replacement. The issue affects 2007+ Suburbans and is one of the most complained-about GM V8 problems. GM switched from 4-cylinder AFM to 17-pattern DFM in 2019, but lifter failures continue.

Traverse owners frequently see 'Service StabiliTrak' and 'Traction Control Off' messages appear together while driving, sometimes accompanied by an engine power reduction. The warning is a downstream symptom rather than a single fault: common triggers are a failing wheel speed sensor, an ABS/EBCM module or wiring-harness fault, or an underlying engine misfire that disables the stability system. The intermittent nature makes it frustrating to diagnose without scanning stored codes.