P0301 on 2007-2009 Saturn Aura: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2007-2009 Saturn AURA

The Saturn Aura was built on the GM Epsilon platform, sharing its core structure and engines (2.4L LE5, 3.5L LZ4, 3.6L LY7) with the Chevrolet Malibu and Pontiac G6. For these engines, P0301 is a straightforward code that most often points to a component in the coil-on-plug ignition system. While the 3.6L LY7 V6 has a well-documented history of stretched timing chains (per TSB #12-06-01-009F) that can cause random misfires (P0300), a single cylinder misfire like P0301 is less likely to be the primary symptom of a timing issue and more commonly indicates a simpler ignition or fuel delivery fault.

Diagnostic Flowchart

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

Symptoms You May Notice

• Rough or shaky idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Flashing or solid Check Engine Light
• Reduced fuel economy
• Smell of unburnt gasoline from the exhaust
• Engine may be hard to start

Most Likely Causes

1. Failed Ignition Coil 🔴 High Probability → Shop Ignition Coil The individual coil-on-plug ignition systems used in all Aura engines are a very common failure point due to constant exposure to high engine temperatures.
   How to confirm: Swap the ignition coil from cylinder #1 with another cylinder (e.g., cylinder #2 on an I4 or cylinder #3 on a V6). Clear the codes and drive. If the code changes to P0302 or P0303, the coil is faulty.
   Typical fix: Replace the failed ignition coil. It is often recommended to replace the corresponding spark plug at the same time.
   Est. part cost: $35-$75
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug Spark plugs are a regular maintenance item with a finite lifespan. If they are past their 100,000-mile service interval, they are a primary cause of weak spark and misfires.
   How to confirm: Remove the spark plug from cylinder #1 and inspect it for wear (rounded electrode), heavy carbon fouling, oil contamination, or cracks in the white ceramic insulator.
   Typical fix: Replace the spark plug. It is best practice to replace all spark plugs at the same time to ensure even performance across all cylinders.
   Est. part cost: $8-$20 per plug
3. Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: Use a mechanic's stethoscope or a long screwdriver to listen for a consistent clicking sound from the injector. If it's silent or has an irregular tick, it may be failing. A professional can perform an injector balance test to confirm flow rate.
   Typical fix: Replace the faulty fuel injector. Sometimes, running a quality fuel system cleaner can resolve minor clogging issues.
   Est. part cost: $50-$120
4. Intake Manifold Gasket Leak ⚪ Low Probability → Shop Engine Intake Manifold The intake gaskets on the GM V6 engines in particular can degrade over time, causing a vacuum leak near a specific cylinder. This allows unmetered air to enter, leaning out the air/fuel mixture and causing a misfire.
   How to confirm: With the engine running, carefully spray brake cleaner or short bursts of propane (unlit) around the intake manifold gasket area for cylinder #1. If the engine idle speed changes or stumbles, a leak is present. A professional smoke test is the most definitive diagnostic method.
   Typical fix: Replace the intake manifold gaskets.
   Est. part cost: $40-$80

Rare But Worth Checking

• Damaged Wiring or Connector to Injector/Coil: The wiring or plastic connector for the ignition coil or fuel injector can become brittle and break, causing an intermittent open circuit and misfire. In one documented case on a 2009 Aura, a broken wire right at the fuel injector connector for cylinder #1 was the root cause of a persistent P0301 after the plug and injector had already been replaced.
• Low Engine Compression: This indicates a more serious internal engine problem, such as a worn piston ring, a bad valve, or a leaking head gasket. A compression test is needed to diagnose this and should be performed if ignition and fuel system checks do not resolve the issue.
• Fuel Contamination: TSB #PIP3333C notes that intermittent misfires on cylinder #1 can occur during or after a left turn. This is caused by contaminants (like water or debris) in the fuel tank sloshing and getting trapped in the returnless fuel rail, temporarily clogging the #1 injector.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0301 is present and note any other codes.
2. Note if the Check Engine Light is solid or flashing. A flashing light indicates a severe misfire that could damage the catalytic converter.
3. Identify the location of cylinder #1 for your specific engine (2.4L, 3.5L, or 3.6L). For V6 models, it's the front cylinder on the bank near the firewall.
4. Swap the ignition coil from cylinder #1 with an adjacent cylinder (e.g., cylinder #3 on a V6, or cylinder #2 on an I4).
5. Clear the codes with the scanner and start the engine. Let it run or drive it for a few minutes.
6. Re-scan for codes. If the code has moved to the cylinder where you placed the coil (e.g., P0303 or P0302), the ignition coil is the culprit and needs replacement.
7. If the code remains P0301, inspect the spark plug in cylinder #1. Check the spark plug tube for oil, which would indicate a leaking valve cover gasket that can damage the coil boot.
8. If the coil and plug are good, inspect the wiring and connector at the cylinder #1 fuel injector and ignition coil for any breaks, corrosion, or loose connections.
9. Listen to the fuel injector for a steady clicking sound. If silent or erratic, it may be faulty.
10. If ignition and fuel components are ruled out, check for vacuum leaks near cylinder #1's intake runner using brake cleaner or a smoke machine.
11. As a final step for persistent issues, perform an engine compression test to check for mechanical problems like bad valves or piston rings.

Parts You'll Likely Need

• Ignition Coil (OEM #3.6L V6: 12632479 (or superseding D522C); 2.4L I4: 12638824 (or UF491); 3.5L V6: 19432144 (or 12595088)) — This is the most common failure part for a single-cylinder misfire on the Saturn Aura's coil-on-plug ignition system.
  Trusted brands: ACDelco, Delphi, NGK, Denso
  OEM price range: $60-$90
  Aftermarket price range: $35-$65
• Spark Plug (OEM #ACDelco 41-103 (Iridium for 2.4L), ACDelco 41-990 (Platinum for 3.5L/3.6L)) — Spark plugs are a primary wear item and a frequent cause of misfires. They should be replaced at regular intervals and are often replaced with a failed coil.
  Trusted brands: ACDelco, NGK, Denso, Bosch
  OEM price range: $10-$15
  Aftermarket price range: $8-$12
• Fuel Injector — A clogged or electrically failed fuel injector is a common medium-probability cause for a single-cylinder misfire.
  Trusted brands: ACDelco, Standard Motor Products (SMP), Bosch
  OEM price range: $90-$150
  Aftermarket price range: $50-$100

Related Codes That Often Appear With This One

• P0300 — If the cause of the misfire, such as a large vacuum leak or low fuel pressure, begins to affect other cylinders, a P0300 (Random/Multiple Cylinder Misfire) code may appear alongside P0301.
• P0302, P0303, P0304, P0305, P0306 — If multiple ignition coils or spark plugs are failing around the same time, you may see misfire codes for other specific cylinders. TSB #PIP3333C also notes that P0301 can appear with P0304 due to fuel contamination issues.

Technical Service Bulletins (TSBs) & Recalls

• PIP3333C: Addresses intermittent engine misfires on codes P0300, P0301, and/or P0304, specifically pointing to fuel contamination in the fuel rail as a possible cause during turns.
• 12-06-01-009F: While not a direct cause of P0301 typically, this TSB addresses premature timing chain wear on the 3.6L V6, which can lead to random misfires (P0300) and is an important issue for owners of this engine to be aware of.

Platform-Specific Known Issues

• Fuel Contamination Misfire (TSB PIP3333C): TSB #PIP3333C describes a unique scenario where an intermittent P0301 can occur during or after a sharp left turn. This is caused by contaminants in the fuel tank sloshing into the fuel rail and temporarily restricting the injector for cylinder #1. The fix involves inspecting the fuel rail and tank for debris.
• Broken Fuel Injector Wiring: → Shop Fuel Injector Owners have reported that after replacing coils and plugs, the P0301 code persisted. The ultimate cause was found to be a broken wire directly at the electrical connector for the cylinder #1 fuel injector, which is a difficult-to-spot failure.