P0304 on 2012-2015 Chevrolet Malibu: Cylinder 4 Misfire Causes and Fixes

What's Unique About the 2012-2015 Chevrolet MALIBU

This year range covers two Malibu generations with different engines, but the causes for P0304 are largely consistent. A notable issue documented by GM is TSB PIP3333C, which points to a unique fuel system problem where debris can get trapped in the fuel rail and clog the #4 injector specifically during right-hand turns. Additionally, owner complaints and forum discussions strongly suggest the 2.4L Ecotec engine (in 2012 models and 2013-14 eAssist) is prone to piston ring issues leading to excessive oil consumption, which fouls the spark plug in cylinder 4 and can eventually cause low compression, resulting in a more serious P0304 fault.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: The 2012-2015 range covers the end of the 7th generation and the start of the 8th. - 2012 (7th Gen): Offered with a 2.4L I4 (LE9) or a 3.6L V6 (LFX) engine. - 2013-2015 (8th Gen): Offered with a 2.5L I4 (LCV/LKW), a 2.0L Turbo I4 (LTG), or a 2.4L eAssist hybrid (LUK) (2013-14 only). The diagnostic process for P0304 is similar across all engines, but part numbers differ.

Symptoms You May Notice

• Check Engine Light is on or flashing
• Rough or shaking idle
• Noticeable loss of engine power and sluggish acceleration
• Reduced fuel economy
• Engine hesitates or stumbles
• Smell of unburned gasoline from the exhaust
• "Service ESC", "Service Stabilitrak" or "Service Traction" messages may appear on the dash, especially at idle. This is because the engine's instability is detected by the chassis control systems, which then disable themselves as a precaution.

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability Coil-on-plug ignition systems are common points of failure due to constant heat cycles and vibration. It's a frequent maintenance item on most modern vehicles, including all Malibu engines from this period.
   How to confirm: Swap the ignition coil from cylinder 4 with another cylinder (e.g., cylinder 2). Clear the codes and drive. If the code changes to P0302, the coil is faulty.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace all coils and spark plugs at the same time 🎬 Watch: Step-by-step ignition coil and spark plug replacement guide. for long-term reliability, especially on higher mileage vehicles.
   Est. part cost: $40-$70
2. Worn or Fouled Spark Plug 🔴 High Probability
   How to confirm: After ruling out the coil, remove the spark plug from cylinder 4. Inspect for a worn electrode, cracks in the porcelain, or heavy carbon/oil deposits. An oil-fouled plug on a 2.4L engine is a strong indicator of the piston ring issue.
   Typical fix: Replace the spark plug. Plugs should be replaced at regular service intervals. Use the correct type (typically Iridium for these engines). Note that ACDelco Iridium plugs are pre-gapped and should not be adjusted.
   Est. part cost: $10-$25
3. Clogged or Faulty Fuel Injector 🟡 Medium Probability
   How to confirm: Listen to the injector with a mechanic's stethoscope; it should make a consistent clicking sound. You can also test the injector's resistance with a multimeter or have a professional flow test performed. On 2.5L engines, the injectors are under the intake manifold and are more difficult to access.
   Typical fix: Replace the fuel injector for cylinder 4. Sometimes a professional fuel system cleaning can resolve a minor clog. TSB PIP3333C notes that debris can specifically clog the #4 injector during right turns.
   Est. part cost: $50-$150
4. Low Engine Compression ⚪ Low Probability The 2.4L Ecotec engine has a well-documented history of excessive oil consumption caused by faulty piston rings. This leads to oil fouling of plugs and eventually, loss of compression. A forum user with a 2012 Malibu 2.4L documented a P0304 where compression on cylinder 4 was only 90 PSI, which increased to 120 PSI with a wet test, confirming bad rings.
   How to confirm: Perform a compression test on cylinder 4 and compare the reading to the other cylinders. A reading that is significantly lower (more than 15-20% difference) indicates a mechanical problem. A 'wet' test (adding a small amount of oil to the cylinder) that raises compression points to worn piston rings.
   Typical fix: This is a major repair. Depending on the cause, it could require replacing piston rings, cylinder head repair (valves/guides), or a complete engine replacement.
   Est. part cost: $500-$4000+

Rare But Worth Checking

• Fuel Contamination in Fuel Rail: GM TSB #PIP3333C specifically notes that on vehicles with returnless fuel systems, contaminants can get trapped in the fuel rail and intermittently block the #4 fuel injector during a hard right turn, causing a temporary misfire. The bulletin covers a wide range of GM vehicles including the 2004-2015 Malibu.
• Vacuum Leak: A crack in the intake manifold or a leaking gasket near cylinder 4's runner can introduce unmetered air, leaning out the mixture and causing a misfire. This can be diagnosed with a smoke test.

Diagnosis Steps

1. Read the DTCs with an OBD-II scanner. Note the P0304 code and any others present, especially P0300 or C-codes for Stabilitrak.
2. Check the freeze frame data to see the engine conditions (RPM, load, temperature) when the misfire occurred.
3. Locate cylinder 4. On 4-cylinder engines (2.4L, 2.5L, 2.0T), it is the cylinder closest to the transmission (driver's side). On the 3.6L V6, it is the middle cylinder on the left bank (the bank closer to the front of the car).
4. Swap the ignition coil from cylinder 4 with an adjacent cylinder (e.g., cylinder 3). Clear the codes, run the engine, and see if the misfire code moves to P0303. If it does, the ignition coil is bad.
5. If the code remains P0304, inspect the spark plug. Look for wear, damage, or fouling (especially oil fouling on 2.4L engines). Replace if necessary.
6. If the coil and plug are good, inspect the wiring and connector for the cylinder 4 ignition coil and fuel injector for damage or corrosion.
7. Listen to the fuel injector on cylinder 4 with a stethoscope. It should have a steady, rhythmic clicking. Compare its sound to an adjacent injector.
8. Perform a compression test on cylinder 4 and compare its pressure reading to the other cylinders. A significant drop indicates a mechanical issue.
9. If compression is low, perform a cylinder leak-down test to determine if the leak is from piston rings, intake valves, or exhaust valves. This is essential for diagnosing the 2.4L Ecotec piston ring problem.

Parts You'll Likely Need

• Ignition Coil (OEM #12638824 (Also D522C) for 2.4L/2.0T/2.5L) — This is the most common failure point for a single-cylinder misfire due to constant exposure to engine heat and vibration.
  Trusted brands: ACDelco, Delphi, NGK
  OEM price range: $60-$90
  Aftermarket price range: $35-$60
• Spark Plug (OEM #41-121 (Iridium) for 2.5L/2.0T; 41-108 for 2.4L) — As a routine maintenance item, a worn or fouled spark plug is a very common cause of a misfire. Oil fouling from piston ring issues on the 2.4L can also cause this.
  Trusted brands: ACDelco, NGK
  OEM price range: $15-$25
  Aftermarket price range: $8-$15
• Fuel Injector (OEM #12633784 (For 2.5L LCV)) — Can become clogged with deposits or fail electronically, preventing the correct amount of fuel from being delivered to cylinder 4.
  Trusted brands: ACDelco, Bosch, Standard Motor Products
  OEM price range: $90-$150
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or begins to affect other cylinders, a P0300 (Random/Multiple Cylinder Misfire) code may be stored alongside P0304.
• C0561 — On many GM vehicles, the engine control module will disable stability control (ESC) and traction control when a significant engine fault like a misfire is detected, as engine performance is crucial for these systems to work correctly. This results in the 'Service Stabilitrak' message and often stores a chassis code like C0561.
• P0204 — This code for "Cylinder 4 Injector Circuit Malfunction" points specifically to an electrical problem with the injector or its wiring, which would directly cause a P0304 misfire.

Technical Service Bulletins (TSBs) & Recalls

• PIP3333C: Addresses an intermittent misfire on cylinder 1 during left turns and cylinder 4 during right turns, caused by fuel rail contamination. Affects a very wide range of GM 4-cylinder vehicles from 2004-2015.

Platform-Specific Known Issues

• A GM Technical Service Bulletin (#PIP3333C) addresses an intermittent P0304 that can occur during a right turn. It suggests that fuel contaminants can become trapped in the returnless fuel rail and temporarily restrict the #4 fuel injector. This TSB applies to a vast range of GM vehicles, including the 2004-2015 Malibu.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (2.5L LCV Engine) — expected: High impedance, typically between 11 and 14 Ohms.. Failure: A reading significantly outside this range, or an open circuit (infinite resistance), indicates a failed injector coil.
• Engine Compression (2.4L Ecotec) — expected: Approximately 150-180 PSI per cylinder, with less than 15% variation between cylinders.. Failure: A reading of 90 PSI on cylinder 4, which increases to 120 PSI with a 'wet' test (oil added), strongly suggests worn piston rings.

Scan Tool Commands That Help

• GM Tech 2 / GDS2: Cylinder Power Balance Test — Use this function to confirm which cylinder is contributing the least power. The tool deactivates cylinders one by one and measures the corresponding drop in engine RPM. A cylinder that causes a smaller RPM drop when deactivated is the one that is misfiring.
• GM Tech 2 / GDS2: Misfire Data / Cylinder Misfire Counts — Use this to view live and historical misfire counts for each specific cylinder. This can help determine if the misfire is constant or intermittent and under what conditions it occurs, even if it hasn't triggered a CEL yet.

Wiring & Ground Locations

• G103 — On the left rear of the engine compartment, often on the cowl above the brake booster.. This is a critical ground point for the Body Control Module (BCM) and Engine Control Module (ECM). A poor connection here can cause numerous, difficult-to-diagnose electrical faults, including erratic signals to and from the ECM that could mimic injector or coil circuit problems.
• G104 / G106 — On the rear of the engine block or cylinder head (firewall side).. These are primary engine-to-chassis grounds. The ignition coils are grounded through the engine block. If the block itself has a poor ground connection to the chassis and battery, it can cause a weak spark across all cylinders, potentially leading to misfires that may be isolated to the weakest cylinder first.
• ECM Connector (e.g., EG A) — At the Engine Control Module (ECM).. The control wire for the cylinder 4 ignition coil runs to a specific pin (e.g., pin 74 on some 4-cylinder models). Checking for continuity between this pin and the ignition coil connector is the definitive way to rule out a wiring harness break or short.

Real Owner Repair Stories

• BobIsTheOilGuy forum user 'SMB' (2012 Chevrolet Malibu 2.4L with 143,000 miles) — Intermittent P0304, flashing CEL at idle, 'Service ECS' & 'Service Traction' messages at idle.
  ❌ Tried (didn't work) Replacing spark plugs, Swapping ignition coils between cylinders 1 and 4, Checking for vacuum leaks and wiring issues
  ✅ What actually fixed it The root cause was confirmed to be low compression due to bad piston rings. A compression test showed cylinder 4 at 90 PSI, which rose to 120 PSI after a 'wet' test (adding oil to the cylinder), indicating a sealing issue at the rings. The user planned to perform a leak-down test for final confirmation.
• 2CarPros forum user (2013 Chevrolet Malibu (engine not specified)) — P0304, 'Service Stabilitrak' and 'Traction Control' lights, jerky driving, reduced power.
  ❌ Tried (didn't work) Replacing the ignition coil and spark plugs for cylinder 4.
  ✅ What actually fixed it The user replaced the parts but the code and symptoms returned immediately. A dealership technician cleared the codes and advised to monitor if they came back, suggesting the next step would be a more in-depth (and costly) diagnostic to check for issues beyond the basic ignition components, like fuel delivery or mechanical problems. The final fix was not posted, highlighting that plugs/coils are not always the solution.

When the Usual Fixes Don't Work

• In one documented case for a 2012 Malibu 2.4L, the owner replaced spark plugs and swapped ignition coils, but the P0304 code and misfire symptoms persisted. The problem was ultimately traced to low compression in cylinder 4, caused by failing piston rings, a known issue with that specific engine. This highlights that for the 2.4L Ecotec, a compression test should be a high-priority step if plugs and coils do not resolve the misfire.

Model Year Variations Within This Range

• 2013-2015 (8th Gen): The 2.5L LCV engine is a direct-injection design, making it susceptible to carbon buildup on intake valves, which is not an issue for the port-injected 2.4L (2012) or 3.6L V6 engines. This can cause a P0304 that won't be fixed by common ignition or fuel system repairs.
• 2012-2015: TSB PIP5529B notes that on the 2.5L LCV engine, loose intake manifold bolts are a known issue that can cause vacuum leaks, leading to lean conditions and misfires. The fix involves applying threadlocker and re-torquing the bolts.