2016-2018 Malibu, Encore & Cruze Intake Manifold: Diagnosing P1101, PCV Failures, and Vacuum Leaks

Vehicle Fitment and Key Part Numbers

This intake manifold is used across several General Motors vehicles that share the same engine platforms. It is crucial to verify your specific engine before ordering.

• 2016-2017 Chevrolet Malibu: Fits models with the 1.5L turbocharged engine (RPO code LFV). For 2016 models, this applies to the 'New Style' body, which can be identified by the 4th digit of the VIN being 'Z'.
• 2016-2018 Buick Encore: Fits models with the 1.4L turbocharged engine (RPO code LE2).
• 2017 Chevrolet Cruze: Fits models with the 1.4L turbocharged engine (RPO code LE2).

The primary OEM part number has been superseded several times. All the numbers below refer to the same part, with the latest number reflecting the most current design.

• Latest Part Number: 12690468
• Previous Part Numbers: 12678245, 12675734, 12672815, 12668310

Symptoms of a Failing Intake Manifold

A failing intake manifold on these vehicles typically creates a vacuum leak. This allows unmetered air to enter the engine, disrupting the carefully balanced air-fuel ratio. Here are the most common symptoms:

• Check Engine Light: This is often the first sign. Common trouble codes include P0171 (System Too Lean) and P1101 🎬 Watch: How to diagnose these common trouble codes (Intake Air Flow System Performance). These codes indicate the engine's computer is detecting more air than it expects.
• Rough or Unstable Idle: The engine may shake, vibrate, or have fluctuating RPMs at a stop. In severe cases, it can lead to stalling.
• Hissing or Whistling Noise: A vacuum leak can create a distinct hissing or whistling sound from the engine bay, which may change with engine speed.
• Poor Acceleration and Reduced Power: With an incorrect air-fuel mixture, the engine can't perform optimally, leading to sluggish acceleration.
• Increased Oil Consumption: A failed PCV system, often integrated with the manifold, can cause high crankcase pressure, forcing oil past seals and into the combustion chamber.

Known Issues, TSBs, and Recalls

The most significant known issue with this intake manifold is related to the Positive Crankcase Ventilation (PCV) system. There are no specific recalls for this part, but several Technical Service Bulletins (TSBs) address related symptoms.

Plugged PCV Orifice and High Crankcase Pressure (TSB 20-NA-047)

A critical issue for these engines is a plugged PCV orifice within the camshaft cover. This blockage leads to excessive pressure inside the engine's crankcase. This pressure can cause oil leaks from the front or rear crankshaft seals and will often trigger a P1101 trouble code. While the fault is in the camshaft cover's PCV passage, the symptoms are often mistaken for a bad intake manifold. It is crucial to test crankcase pressure before replacing the manifold.

Missing PCV Non-Return Valve (TSB 19-NA-101)

Some older GM 1.4L engines (not the LE2, but a related design) had issues where a non-return check valve inside the intake manifold could become dislodged. This valve is designed to prevent boost pressure from entering the crankcase. If it fails, the boost pressure can rupture the PCV diaphragm in the valve cover. While this TSB doesn't specifically list the LE2 engine, the principle is important. A failure in the PCV system often requires replacing both the valve cover and the intake manifold as a set. Aftermarket companies like Dorman have even redesigned their replacement manifolds to address this failure mode.

Cracked Pistons (TSB 18-NA-171)

In some cases, especially on the 1.4L LE2 engine, a P0300 (Engine Misfire) code can be caused by cracked pistons. This is a serious mechanical failure that can also cause high crankcase pressure. To properly diagnose it, a technician must perform compression and cylinder leakage tests, which may require removing the intake manifold for access.

Buying a Used Engine Intake Manifold

A used OEM intake manifold can be a cost-effective and reliable alternative to an expensive new part. Here’s what to check before you buy:

• Physical Inspection: Carefully inspect the entire plastic body for any hairline cracks, especially around the mounting points and sensor ports. Check the mating surfaces that connect to the cylinder head to ensure they are flat and free of damage.
• Check for Warping: Place the manifold on a known flat surface to check for any warping that could prevent a good seal.
• Included Components: Look for a manifold that comes with the throttle body and MAP sensor still attached. This can save you time and money, but be sure to verify the condition of these extra parts.
• Verify Part Number: Match the part number on the used manifold to one of the known OEM numbers (12690468, 12678245, etc.) to ensure compatibility.
• Low Mileage Donor: If possible, choose a part from a lower-mileage vehicle. Heat cycles and vibrations contribute to the degradation of the plastic over time.
• Why Used OEM?: A used original equipment part is often superior to a new, cheap aftermarket alternative. OEM parts are designed for a perfect fit and are made from high-quality materials tested by the manufacturer. Aftermarket parts can have fitment issues or be made from lower-grade plastic that may not last as long.

Cost to Replace Engine Intake Manifold

Frequently Asked Questions (FAQ)