P0171 on Chevrolet

The 4.3L Vortec V6 uses a central port fuel injection system (nicknamed "spider" for its appearance) that is prone to leaking fuel internally into the intake manifold. The fuel pressure regulator and poppet nozzles develop leaks, causing hard starting, rough idle, and a fuel smell. This is a fire hazard.

Same intake gasket issue as all GM 4.3L vehicles. The composite gaskets fail, allowing coolant leaks. The Astro version is particularly problematic due to the engine positioned under the dash, making repairs more labor-intensive.

Same as the S-10 truck - the 4.3L Vortec V6 develops intake manifold gasket leaks. The Blazer version is identical mechanically.

The early central port injection (CPI) system uses pressurized fuel lines under the upper intake manifold that develop cracks and leaks over time. Fuel leaks directly onto the hot engine, creating a serious fire hazard. The plastic fuel lines become brittle with age and heat exposure.

The 5.7L Vortec V8 (1996-1999) uses a Central Port Injection (CPI) spider assembly with poppet nozzles that clog and leak fuel. The plastic fuel lines become brittle and crack, causing hard starts, rough idle, and fuel odor.

Both the 2.2L OHV and 2.4L Twin Cam engines in the Cavalier are prone to head gasket failure. The 2.4L is particularly susceptible due to the aluminum head and iron block thermal expansion differences.

GM 3.1L V6 intake gaskets use a plastic carrier that warps and leaks coolant into the oil or externally. One of the most common failures on this engine across all GM platforms.

The 1.4T engine in the first-generation Cruze has the PCV system integrated into the valve cover assembly. The PCV diaphragm ruptures, the check valve fails, or the valve cover gasket deteriorates, causing oil leaks, vacuum leaks, rough idle, and check engine lights. The failed PCV system creates excess crankcase pressure that pushes oil past seals and into the intake manifold. This is the same fundamental design flaw as the Equinox and Malibu 1.5T PCV system. GM released an updated valve cover with improved PCV components.

The 2.4L Ecotec engine uses low-tension piston rings that fail to maintain proper tension to keep oil in the crankcase. Vehicles consume 1 quart of oil per 800-1,000 miles. This defect can cause premature engine wear, engine failure, and potential fire risk if oil levels drop critically low. GM acknowledged this defect through TSBs and class action settlements.

A defective oil filter adapter can cause engine oil leaks that may contact hot exhaust components, creating a fire risk. Combined with the excessive oil consumption issue, low oil conditions can exacerbate the problem.

Vortec V8 intake manifold gaskets deteriorate causing coolant and oil leaks. Common on high-mileage vans, can lead to coolant contamination of oil if ignored.

The 3.4L and 3.8L V6 engines in 2000-2005 Impalas use Dex-Cool compatible intake manifold gaskets that deteriorate over time, causing coolant to leak externally or internally into the oil. External leaks appear as dried orange coolant trails on the engine block. Internal leaks contaminate the engine oil with coolant, turning it into a milky sludge that can destroy the engine bearings. This was one of the most widespread GM engine problems of the era and led to multiple class-action lawsuits.

The 3.1L and 3.4L pushrod V6 engines in the Lumina develop intake manifold gasket leaks, often attributed to Dex-Cool coolant reacting with the composite gaskets. Coolant leaks externally and can also enter the crankcase.

The 2.5L Ecotec 4-cylinder engine in the 2013-2020 Malibu consumes oil at a rate well beyond what GM considers normal, with some owners reporting 1 quart every 1,500-2,000 miles. The piston rings do not properly seat against the cylinder walls, allowing oil to pass into the combustion chamber. The issue is exacerbated by the use of 0W-20 oil specified by GM. There is no visible external leak — the oil is burned internally and exits through the exhaust.

The 3.8L Series II V6 develops intake manifold gasket leaks and the plastic coolant elbow on the front of the engine cracks. The supercharged SS models also have supercharger snout wear causing boost leaks.

The 1994-2004 S-10 in-tank fuel pump is prone to premature failure. Running the tank below 1/4 accelerates pump death because fuel cools and lubricates the pump. The integrated fuel level sender also fails, causing erratic gauge readings. Hot restart problems are a classic early warning sign as heat exacerbates pump weakness.

The "spider" fuel injection system in the 4.3L Vortec V6 uses a central injector assembly with poppet nozzles connected by fuel lines. The poppet nozzles stick and leak, causing rough running, hard starting, and fuel smell. The original design was replaced by an updated MPFI system that uses actual injectors at each port.

The 4.3L Vortec V6 develops intake manifold gasket leaks that allow coolant to leak externally or mix with engine oil. The plastic gaskets deteriorate from heat cycling. This is a very common problem on all GM 4.3L V6 trucks.

The 1.4L turbocharged Ecotec engine in the Sonic shares the notorious PCV system failure with the Chevrolet Cruze. The PCV regulator diaphragm integrated into the valve cover ruptures, causing massive vacuum leaks. Additionally, the intake manifold check valve (small red/orange valve) fails, compounding the issue. This affects virtually all 1.4T Sonics eventually, typically between 50,000-100,000 miles.

The small-displacement turbo engines in the Trailblazer can consume oil between changes, particularly the 1.2L 3-cylinder. Some owners report needing to add oil between the 7,500-mile change intervals.

The 3.5L and 3.9L V6 develop intake manifold gasket leaks, continuing the GM V6 gasket legacy. Coolant leaks externally or into engine oil.