P0204 on 2007-2009 Saturn Aura 3.6L: Injector Circuit Malfunction - Cylinder 4 Causes and Fixes

What's Unique About the 2007-2009 Saturn Aura

The Saturn Aura shares its 3.6L V6 (LY7) engine and GM Epsilon platform with many other vehicles like the Pontiac G6 and Chevy Malibu. A well-documented issue across these models is the fuel injector wiring harness chafing against engine components. GM Technical Service Bulletin (TSB) #PIP4924D specifically addresses engine misfires and injector circuit codes (P0201-P0206) caused by the harness rubbing on the intake plenum, valve cover bolts, or fuel lines. This makes a wiring inspection a critical first step before replacing any parts. One owner of a platform-mate (2008 GMC Acadia) with codes P0202, P0204, and P0206 traced the issue to a wiring integrity problem near the fuse box.

Symptoms You May Notice

• Check Engine Light is on
• Engine misfire, which may feel like shaking or stumbling, especially at idle
• Reduced engine power and poor acceleration
• Rough or unstable idle
• Decreased fuel economy
• Engine may hesitate or stall
• Strong smell of raw fuel from the exhaust

Most Likely Causes

1. Faulty Fuel Injector (Cylinder 4) 🔴 High Probability → Shop Fuel Injector The fuel injectors on the 3.6L V6 are a common failure item across multiple GM platforms that use the LY7 engine.
   How to confirm: Measure the injector's resistance with a multimeter (should be 11-14 ohms for the LY7 engine). The most definitive test is to swap the cylinder 4 injector with an adjacent one on the same bank (e.g., cylinder 2 or 6). Clear the codes; if the code changes to P0202 or P0206, the injector is faulty.
   Typical fix: Replace the failed fuel injector. Accessing the injectors on the 3.6L V6 requires removing the upper intake manifold. 🎬 See this walkthrough for removing the intake and injectors.
   Est. part cost: $40-$90
2. Wiring Harness Issue (Open or Short Circuit) 🟡 Medium Probability GM TSB #PIP4924D specifically calls out the potential for the injector wiring harness to chafe on V6 models, causing an open or short in the circuit. Common chafe points are against the intake manifold, valve covers, fuel lines, and cylinder head.
   How to confirm: Perform a thorough visual inspection of the wiring harness leading to the cylinder 4 injector. Check for any signs of rubbing, melting, or broken wires. Use a multimeter to check for continuity between the PCM connector and the injector connector. A 'wiggle test' on the harness while the engine is running can sometimes expose an intermittent short or open.
   Typical fix: Repair the damaged section of wire and secure the harness away from any sharp edges or hot surfaces using zip ties and protective wire loom like PET woven polyester tape.
   Est. part cost: $5-$25
3. Poor Connection at Injector or PCM ⚪ Low Probability Engine vibration can cause the electrical connector terminals to become loose or corroded over time, a condition known as 'fretting,' which creates high resistance. This is a common issue on many GM vehicles. A loose retaining clip on the connector can also cause an intermittent connection.
   How to confirm: Disconnect the connector at the fuel injector and inspect the pins for corrosion (green or white powder) or fretting (black powder). Ensure the connector clicks firmly into place and the retaining clip is secure. Perform a 'wiggle test' on the connector while the engine is running to see if it affects the misfire.
   Typical fix: Clean the connector terminals with electrical contact cleaner and apply dielectric grease to prevent future corrosion. If terminals are loose or damaged, the connector pigtail may need to be replaced.
   Est. part cost: $10-$30

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is the least likely cause. The PCM's internal driver for the injector circuit can fail, but all other possibilities should be exhausted before considering PCM replacement.

Diagnosis Steps

1. Verify the code P0204 is present using an OBD-II scanner. Check for any other codes, especially P0304, P0202, or P0206.
2. Locate cylinder #4. On the transverse LY7 3.6L V6, the front bank (closest to the radiator) is cylinders 2-4-6 from left to right (passenger to driver side). Cylinder 4 is the middle cylinder on the front bank, making it relatively easy to access.
3. Perform a thorough visual inspection of the wiring harness and connector for the cylinder 4 fuel injector. Pay close attention to areas where the harness might rub against the intake manifold, valve covers, fuel lines, or cylinder head, as noted in TSB #PIP4924D.
4. If no visible damage is found, disconnect the injector and plug a 'noid light' into the connector. Crank the engine. The light should flash steadily. If it doesn't flash, there is a problem with the wiring or the PCM. If it stays on constantly, there is a short to ground in the circuit.
🎬 Watch: How to test the injector circuit using a test light.
5. If the noid light flashes correctly, the problem is likely the injector itself. Turn the engine off.
6. Use a multimeter to measure the resistance of the fuel injector. It should be between 11 and 14 ohms. An open circuit (infinite resistance) or a short (near zero resistance) indicates a failed injector.
7. For a definitive diagnosis, swap the cylinder 4 fuel injector with the cylinder 2 or cylinder 6 injector (on the same bank). Clear the codes with the scanner and drive the vehicle. If the code returns as P0202 or P0206, the injector is confirmed to be faulty. If P0204 returns, the problem is in the wiring or PCM.

Parts You'll Likely Need

• Fuel Injector (OEM #12638530) — This is the most common part to fail that causes a P0204 code, after ruling out wiring issues. The original part number 12638530 has been superseded by GM part number 12669384.
  Trusted brands: ACDelco, Delphi, Bosch, Standard Motor Products
  OEM price range: $70-$110
  Aftermarket price range: $40-$90
• Fuel Injector Connector Pigtail (OEM #ACDelco PT2183 (check application)) — If the connector itself is damaged or corroded, or if wiring is broken near the connector, replacing the pigtail is the standard repair.
  Trusted brands: ACDelco, Dorman
  OEM price range: $20-$35
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• P0304 — This code means 'Cylinder 4 Misfire Detected.' A fault in the injector circuit prevents fuel from being delivered correctly, which directly causes a misfire on that cylinder.
• P0300 — This code means 'Random/Multiple Cylinder Misfire.' If the wiring harness issue is severe or affects a shared power/ground for multiple injectors, it can cause misfires on more than one cylinder.
• P0202, P0206 — These are injector circuit codes for the other cylinders on the same bank (Bank 2, the front bank). If they appear with P0204, it strongly points to a shared wiring harness problem or a blown fuse for that bank, rather than three injectors failing at once.
🎬 Watch: How to fix multiple injector circuit codes on GM engines.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Instructs technicians to inspect for engine misfires and injector circuit codes (P0201-P0206) due to potential wiring harness chafing on V6 models.

Platform-Specific Known Issues

• A known issue, documented in GM TSB #PIP4924D, involves the fuel injector wiring harness chafing against engine components like the intake plenum, valve cover bolts, fuel lines, or the cylinder head itself. This can cause an open or short circuit, triggering P0204 and other related codes.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance — expected: 11.0 - 14.0 Ohms. Failure: A reading of 0 Ohms (short), infinite/OL (open), or being significantly outside this range indicates a faulty injector coil.
• Fuel Injector Circuit Voltage (Key On, Engine Off) — expected: ~12V (Battery Voltage) on the power feed wire at the injector connector.. Failure: Low or no voltage points to a problem in the power supply circuit, such as a blown fuse (e.g., #43 or #44 in underhood block) or damaged wiring.
• Fuel Pressure Drop during Injector Balance Test — expected: The pressure drop for each injector should be within 20 kPa (3 psi) of the average pressure drop of all injectors.. Failure: A value for cylinder 4 that is significantly different from the others indicates a clogged or malfunctioning injector.

Scan Tool Commands That Help

• GM Tech 2 / GDS2: Fuel Injector Balance Test — Use this after confirming the electrical circuit is intact (e.g., with a noid light). This test commands each injector to fire for a precise duration and measures the resulting drop in fuel rail pressure. It can identify a mechanically faulty or clogged injector that is not flowing correctly, even if its electrical coil is good.
• GM Tech 2 / GDS2: Cylinder Power Balance Test — This is used to confirm which cylinder is not contributing power, helping to verify the misfire is on cylinder 4. The tool sequentially disables each cylinder's injector. If disabling cylinder 4 results in little or no change to engine RPM or smoothness compared to other cylinders, it confirms the fault is isolated to cylinder 4.

Wiring & Ground Locations

• G105 — On the center rear of the 3.6L engine block.. This is a primary engine ground. A loose or corroded connection here can cause unstable voltage references for various actuators, including the fuel injectors, leading to intermittent circuit codes.
• G113 — On the center of the left side cylinder head (front bank).. This ground is specific to the cylinder head where bank 2 (cylinders 2-4-6) is located. A poor connection can directly affect the electrical stability of the injectors on that bank.
• Injector Fuse #43 / #44 — In the underhood fuse block.. The LY7 engine uses separate fuses for the odd and even injector banks. A blown fuse for the even bank (cylinders 2-4-6) will cut power to the cylinder 4 injector, causing a P0204 along with P0202 and P0206.
• ECM (Engine Control Module) — Located in the left side of the engine compartment, in front of the battery.. This is the source of the control signal for the injector. All wiring diagnosis for the control side of the circuit will eventually lead back to the ECM connector.

OEM Part Supersession History

• 12638530 (also 12611545, 12632255) → 12669384 — Standard part revision by GM for improved performance, reliability, or manufacturing efficiency.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Premature Timing Chain Stretch 🔴 High — Very common, especially on earlier LY7 engines. Often occurs between 70,000 and 120,000 miles. Triggers codes like P0008, P0009, P0016, P0017. (Ref: TSB #12-06-01-009F; Special Coverage Adjustment #11340C (expired))
• Power Steering System Faults 🟠 Medium — Commonly reported issue involving the electric power steering pump, control module, or power steering fluid leaks.
• Intake Manifold Gasket / PCV System Vacuum Leaks 🟠 Medium → Shop Engine Intake Manifold — The intake gaskets and PCV tubes are known to fail, causing vacuum leaks that can trigger codes like P0068 and lead to a rough idle.
• Transmission Malfunctions 🔴 High — Owners have reported issues with the 6-speed automatic transmission, including leaks and premature failure requiring rebuilds or replacement. (Ref: Recall #13036 (related to shift cable, not internal failure))
• Knock Sensor Failure/Corrosion 🟡 Low — The knock sensors are located under the intake manifold, where they can be susceptible to moisture and corrosion over time, leading to codes like P0327 or P0332.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For a wiring repair, sourcing a used connector pigtail or a section of wiring harness from a junkyard is a viable, cost-effective option, provided the donor part is in excellent condition.

Donor-vehicle mileage cap: roughly under 100000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For wiring/connectors: Check that the plastic is not brittle, the locking tabs are intact, and the wire insulation is flexible and not cracked from heat.
• Inspect connector pins for any signs of green/white corrosion or black dust (fretting).
• Avoid parts from vehicles with obvious signs of flood or fire damage.

OEM-only on this vehicle (don't cheap out):

• Fuel Injector

Aftermarket brands forum-validated for this vehicle:

• For Fuel Injectors: ACDelco (OE), Bosch, Delphi, Standard Motor Products (SMP).
• For Connector Pigtails: ACDelco, Dorman.

Brands owners have reported issues with on this vehicle:

• Avoid unbranded, 'no-name' fuel injectors from online marketplaces. These often have high failure rates, inconsistent fuel flow, and can cause persistent performance issues.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0304 — Cylinder 4 Misfire Detected — this code often accompanies P0204 because the electrical fault in the injector circuit prevents proper fuel delivery, causing a mechanical misfire.
• P0202 — Injector Circuit/Open - Cylinder 2 — another injector circuit code frequently mentioned alongside P0204 in TSB #PIP4924D regarding wiring harness chafing on the V6 engine.
• P0206 — Injector Circuit/Open - Cylinder 6 — part of the same front cylinder bank as cylinder 4; often triggered by the same wiring harness chafing issues described in GM TSBs.
• P0008 — Engine Position System Performance Bank 1 — a common code on the LY7 engine related to premature timing chain stretch, which may be checked when diagnosing general engine performance issues.
• P0068 — MAP/MAF - Throttle Position Correlation — can be triggered by vacuum leaks in the intake manifold gaskets or PCV system, which are known issues on this vehicle.

Frequently Asked Questions