P0273 on 2009-2010 Saturn Outlook: Cylinder 5 Injector Circuit Low Causes and Fixes

What's Unique About the 2009-2010 Saturn OUTLOOK

The Saturn Outlook shares its 3.6L V6 engine and chassis with the GMC Acadia, Buick Enclave, and Chevrolet Traverse. This entire GM Lambda platform is known for a specific wiring harness vulnerability. A Technical Service Bulletin (TSB PIP4924D) confirms the fuel injector harness is prone to rubbing against engine components, causing wires to chafe and short out. Specific chafe points mentioned in the TSB are against the intake plenum, valve cover bolts, the EVAP canister purge solenoid valve bracket, fuel lines, or the side of the cylinder head. This makes a wiring fault a much higher probability for code P0273 on this vehicle compared to a random injector failure.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Rough or shaking idle
• Engine hesitation or stumbling on acceleration
• Noticeable loss of power
🎬 Watch: A quick guide to understanding the P0273 engine code.
• Poor fuel economy
• A tapping or popping sound from the engine bay
• Engine may go into 'Reduced Power Mode'

Most Likely Causes

1. Chafed/Damaged Fuel Injector Wiring Harness 🔴 High Probability → Shop Engine Wiring Harness As documented in GM Technical Service Bulletin #PIP4924D, the harness routing on the 3.6L V6 makes it susceptible to rubbing. Specific chafe points are against the intake plenum, valve cover bolts, the EVAP canister purge solenoid valve bracket, fuel lines, or the side of the cylinder head. This is the most common cause across the entire Lambda platform.
   How to confirm: Visually inspect the entire length of the fuel injector wiring harness for the rear bank of cylinders (Bank 1), especially where it contacts other components. Peel back any plastic loom and look for shiny copper wire, melted insulation, or obvious rub marks. Wiggling the harness with the engine running may cause a change in idle quality, helping to pinpoint the short.
   Typical fix: Repair the damaged section of wire with a quality weatherproof butt connector and heat-shrink tubing. Protect the repaired area with anti-abrasion tape or new loom and secure it away from sharp edges. If damage is near the connector, replace the pigtail (e.g., ACDelco PT2160, Dorman 645-215).
   Est. part cost: $5-$40
2. Faulty Cylinder 5 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector The direct injection (DI) injectors on the 3.6L LLT engine operate under very high pressure and can fail electrically from an internal short circuit. While less common than the wiring issue, it is a frequent failure point.
   How to confirm: After confirming the wiring is intact, swap the cylinder 5 injector with an injector from another cylinder (e.g., cylinder 3). Clear the codes. If the code returns as P0267 (Cylinder 3 Injector Circuit Low), the injector is faulty. You can also test the injector's resistance with a multimeter. For the LLT direct injection engine, it should be between 1.5-1.6 Ohms. A reading near zero indicates a short.
   Typical fix: Replace the faulty fuel injector. Accessing the injector requires removing the upper intake manifold, so you will also need to replace the intake manifold gaskets. 🎬 See this walkthrough for removing the intake and replacing injectors. It is often recommended to replace the Teflon seal on the new injector.
   Est. part cost: $40-$120
3. Poor Connection at Injector or ECM ⚪ Low Probability Engine vibration and heat can cause the USCAR-style injector connector or the main harness connectors (X160/X161 at the rear of the intake) to become loose or corroded.
   How to confirm: Inspect the electrical connector at the cylinder 5 injector and the main engine harness connectors for loose fit, corrosion, or bent/backed-out pins. Clean with electrical contact cleaner and apply dielectric grease before reconnecting.
   Typical fix: Clean and secure the connector. If the connector or its pins are damaged, replace the connector pigtail.
   Est. part cost: $15-$40

Rare But Worth Checking

• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is the least likely cause. The internal driver circuit for the cylinder 5 injector can fail within the ECM. This should only be considered after all wiring and the injector itself have been proven to be good. A professional scan tool can perform an actuator test to confirm driver failure.

Diagnosis Steps

1. Read all stored fault codes with an OBD-II scanner. Note if P0305 or other injector codes are present.
2. Identify Cylinder 5: On the transverse 3.6L engine, the cylinders against the firewall are Bank 1 (odd numbers: 1-3-5, from passenger to driver side). Cylinder 5 is the middle cylinder on the rear bank.
3. Thoroughly inspect the fuel injector wiring harness for any signs of chafing, melting, or damage. Pay extremely close attention to the TSB #PIP4924D locations: where the harness touches the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head.
4. Inspect the electrical connector on the cylinder 5 injector for a secure fit, corrosion, or damaged pins.
5. If wiring appears good, use a 'noid light' to test for a signal at the injector connector while cranking the engine. A steady flashing light indicates the ECM is sending a signal.
6. If a signal is present, test the injector. The most definitive test is to swap the cylinder 5 injector with one from another cylinder on the same bank (e.g., cylinder 3).
7. Clear the codes and drive the vehicle. If the code changes to P0267 (for cylinder 3), the injector is bad and must be replaced.
8. If code P0273 returns after the swap, the fault is in the wiring between the ECM and the injector connector. Perform a continuity test on the wires.
9. If all other tests pass, the ECM may be faulty, but this is extremely rare and should be professionally diagnosed.

Parts You'll Likely Need

• Fuel Injector Wiring Harness Pigtail (OEM #ACDelco PT2160) — If the wiring is damaged right at the USCAR-style connector, replacing the pigtail is the standard repair.
  Trusted brands: ACDelco, Dorman (e.g., 645-215)
  OEM price range: $30-$50
  Aftermarket price range: $15-$30
• Fuel Injector (OEM #12638530 (superseded by 12669384)) — If the injector itself has failed with an internal short, it will need to be replaced. This is the second most common cause after wiring issues.
  Trusted brands: ACDelco, Bosch, Hitachi
  OEM price range: $70-$120
  Aftermarket price range: $40-$80
• Upper Intake Manifold Gasket Set (OEM #Fel-Pro MS 97240-1 (Set)) — This is required for replacing the fuel injector, as the intake manifold must be removed to access the rear bank of cylinders. These gaskets are single-use and must be replaced to prevent vacuum leaks.
  Trusted brands: ACDelco, Fel-Pro
  OEM price range: $25-$40
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• P0305 — P0305 means 'Cylinder 5 Misfire Detected'. Since the P0273 code indicates the injector for cylinder 5 is not working correctly, it directly causes that cylinder to misfire.
🎬 Watch: A helpful explanation of why your engine is misfiring.
• P0205 — This is a more general code for 'Cylinder 5 Injector Circuit Malfunction'. It often appears with the more specific 'Circuit Low' code P0273 as they both relate to the electrical integrity of the same circuit.
• P0261, P0264, P0267, P0270, P0276 — These are 'Circuit Low' codes for the other cylinders. If multiple codes appear at once, it strongly suggests a widespread wiring harness issue where several wires have been damaged at the same time.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Addresses engine misfires and a list of injector circuit codes (including P0273) that may be caused by the fuel injector wiring harness rubbing through. It advises a thorough inspection of the harness where it may contact the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head before replacing any parts.

Platform-Specific Known Issues

• The fuel injector wiring harness is known to rub through against engine components, as documented in GM TSB #PIP4924D. This is the most common cause of P0273 on this vehicle.
• Cylinder 5 is on the rear bank of the engine (Bank 1), close to the firewall. Accessing the injector and its wiring requires removing the upper intake manifold, which adds significant labor time and complexity to the repair.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (3.6L LLT Engine) — expected: 1.5 - 1.6 Ohms. Failure: A reading near zero ohms indicates a short; an infinite reading (OL) indicates an open circuit. Some sources state a slightly wider but still low range of 11.8-12.6 Ohms, which may apply to a different variant; however, multiple sources confirm the ~1.5 Ohm reading for the LLT direct injector.
• Low-Side Fuel Pressure (at fuel tank pump) — expected: 58-60 PSI. Failure: Pressure significantly below this range indicates a weak in-tank fuel pump, which can cause drivability issues but will not directly cause a P0273 circuit code.
• High-Side Fuel Pressure (at fuel rail, engine running) — expected: Up to 1,740 PSI (120 bar), varies with engine demand.. Failure: Inability to build pressure under load points to a failing High-Pressure Fuel Pump (HPFP), but this would typically set different codes related to fuel pressure, not a specific injector circuit code.
• Injector Circuit Voltage (at injector connector, Key On Engine Off) — expected: 11.5 - 12.5 Volts (Battery Voltage). Failure: Voltage below 10V suggests a problem upstream in the wiring harness or with the power supply from the ECM.

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Fuel Injector Balance Test — After verifying the electrical circuit is intact, this bidirectional test commands each injector to fire and measures the resulting fuel pressure drop. It can definitively identify a mechanically failed (clogged or stuck) injector versus an electrical fault, helping to avoid unnecessary injector replacement if the fault is in the wiring.
• GM GDS2 / Tech 2: Injector Test / Active Fuel Injector Test (AFIT) — This function allows the technician to disable one injector at a time while the engine is running. If disabling cylinder 5 causes no change in the engine's idle, it confirms that cylinder 5 was not contributing, which is the expected result for a P0273 fault.

Wiring & Ground Locations

• G112 — Rear of the engine, mounted to the rear of the cylinder head (Bank 1 side).. This is a primary engine ground point for Bank 1, which includes cylinder 5. A loose or corroded connection at G112 can cause erratic voltage and intermittent low circuit codes for any sensor or actuator on that bank, including the fuel injectors.
• ECM Connector X1 — The main 72-pin connector at the Engine Control Module (ECM).. This is the primary test point for checking continuity of the injector wiring without removing the intake manifold. Technicians can test the circuit from the ECM pins for the cylinder 5 injector all the way to the injector connector to isolate a break or short in the harness.
• Cylinder 5 Injector Control Wires — Within the engine harness, running from the ECM X1 connector to the cylinder 5 injector.. These specific wires (typically a twisted pair, one for high-side driver, one for low-side control) are the subject of the P0273 code. For the LLT, the ECM controls both the high and low side. A short to ground on the control wire is the most common trigger for the code. A wiring diagram is essential to identify the correct wire colors and pin numbers at the ECM.

Real Owner Repair Stories

• acadiaforum.net user (2009 GMC Acadia (Lambda Platform Twin)) — Check engine light with codes P0273, P0300, and P0305. Rough idle and misfire.
  ❌ Tried (didn't work) Initial diagnosis suggested a bad injector or coil.
  ✅ What actually fixed it The owner inspected the wiring harness as per TSB PIP4924D and found a wire that had chafed through its insulation where it was rubbing against the engine block. The wire was repaired, protected with loom, and secured away from the contact point, which resolved all codes and symptoms.

OEM Part Supersession History

• 12611545 → 12632255, then 12638530, then 12669384 — Standard part evolution for design improvements, material changes, or manufacturing updates.
  Heads up: While these parts are generally interchangeable for the 2009-2010 LLT engine, it is always best practice to replace injectors in a set or at least on the same bank to ensure matched flow rates. The latest part number, 12669384, is the current service replacement.