P0276 on 2009-2014 Buick LaCrosse: Cylinder 6 Injector Circuit Low Causes and Fixes

What's Unique About the 2009-2014 Buick LACROSSE

For this generation of Buick LaCrosse and many other GM vehicles sharing the 3.0L (LF1/LFW) and 3.6L (LLT/LFX) V6 engines, code P0276 is frequently caused by a wiring issue rather than a failed fuel injector. GM issued Technical Service Bulletin #PIP4924D, which specifically warns technicians about the fuel injector wiring harness rubbing through where it's routed. Common chafe points include contact with the intake plenum, valve cover bolts, fuel lines, or the side of the cylinder head. This known vulnerability makes inspecting the wiring harness the most critical first step in diagnosis, saving time and money on unnecessary injector replacement.

Diagnostic Flowchart

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

Generation note: The 2009-2014 year range covers the end of the first generation (2005-2009) and the majority of the second generation (2010-2016) LaCrosse. This code and its common causes apply to the V6 engine options in both generations. The TSB #PIP4924D specifically lists the 2009-2014 LaCrosse, confirming the wiring issue is a known problem across this entire period.

Symptoms You May Notice

• Check Engine Light is on (may be flashing in severe cases)
• Rough or shaking idle
• Reduced engine power and poor acceleration
• Engine hesitation or stumbling
• Decreased fuel economy
• A smell of raw fuel from the exhaust
• Engine may stall intermittently

Most Likely Causes

1. Damaged Fuel Injector Wiring Harness 🔴 High Probability → Shop Engine Wiring Harness As documented in GM TSB #PIP4924D, the injector wiring harness is known to rub against components like the intake plenum, valve cover bolts, fuel lines, or the side of the cylinder head, causing wires to chafe and short to ground or break. This is the most common failure point for this specific code on this platform.
   How to confirm: Perform a careful visual and physical inspection of the entire fuel injector wiring harness, especially at the back of the engine and around the cylinder heads. A YouTuber working on a 9th Gen Impala with the same LFX engine and P0276 code traced the harness looking for this exact issue. 🎬 Watch: This mechanic finds the exact harness rub point. Look for any signs of rubbing, melting, or exposed copper wire. Wiggle the harness with the engine running to see if it affects the misfire.
   Typical fix: Repair the damaged section of wire using solder and heat-shrink tubing. Protect the harness from future rubbing using high-temp split loom or by re-routing it. If the damage is near the connector, a new pigtail connector (like ACDelco PT2618) may need to be spliced in.
   Est. part cost: $15-$50
2. Failed Cylinder 6 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector Injectors can fail electrically over time due to internal coil windings breaking down. While less common than the wiring issue on this platform, it is still a significant possibility.
   How to confirm: If wiring is intact, test the injector. Use a multimeter to check the resistance across the injector's two terminals. For the 3.6L V6, it should be between 1.2 and 1.8 ohms. An open circuit (infinite resistance) or short (near zero resistance) means the injector is bad. You can also swap the injector with an adjacent cylinder (e.g., cylinder 4) and see if the code follows to the new cylinder (e.g., P0270). Cylinder 6 is on the front bank (Bank 2), closest to the radiator, on the driver's side.
   Typical fix: Replace the faulty fuel injector. It is often recommended to replace all injectors on the same bank (or all six) if they are original and have high mileage. Ensure the new injector is oriented correctly as per GM guidelines to prevent cold start misfires. 🎬 See this walkthrough for replacing injectors on the LFX engine.
   Est. part cost: $40-$120
3. Corroded or Loose Injector Connector ⚪ Low Probability Moisture and engine bay heat can degrade the plastic and metal contacts over time.
   How to confirm: Unplug the electrical connector at the cylinder 6 fuel injector and inspect the pins on both the injector and the connector for green or white corrosion, moisture, or damaged/spread pins. Ensure it fits securely with a 'click' when reconnected.
   Typical fix: Clean the connector pins with electrical contact cleaner and a small brush. Apply a small amount of dielectric grease to the seal. If the connector is damaged or won't stay secure, replace the connector pigtail.
   Est. part cost: $15-$40

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is the least likely cause. The internal driver circuit for the cylinder 6 injector can fail, but all other possibilities, especially wiring, should be exhaustively ruled out before condemning the PCM.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner and note any other codes present, especially P0306.
2. Crucially, perform a detailed visual inspection of the fuel injector wiring harness, as recommended by TSB #PIP4924D. Check for chafing against the intake, valve covers, fuel lines, and the side of the cylinder head. Pay close attention to the harness section that runs along the back of the engine.
3. Inspect the electrical connector at the cylinder 6 fuel injector (front bank, driver's side). Look for corrosion, bent pins, or a loose connection.
4. Use a 'noid light' to test the injector connector. The light should flash consistently when the engine is cranked or running, indicating the PCM is sending a signal. If it does not flash or is very dim, the problem is in the wiring or PCM.
5. If the noid light flashes correctly, turn off the engine and disconnect the injector. Use a multimeter to measure the resistance of the fuel injector. For the 3.6L V6, the reading should be between 1.2 and 1.8 ohms. If it's out of spec, the injector has failed.
6. If the noid light does not flash, check for continuity on both wires running from the injector connector back to the PCM connector to rule out a broken wire. Check each wire for a short to ground.
7. As a final confirmation, swap the cylinder 6 injector with another cylinder (e.g., cylinder 4 on the same bank). If the misfire code moves to the new cylinder (P0304), the injector is faulty. If the P0276/P0306 codes remain, the issue is confirmed to be in the wiring or PCM.
8. If wiring and the injector are confirmed to be good, the issue may be with the PCM's injector driver, which is rare.

Parts You'll Likely Need

• Fuel Injector Wiring Harness Pigtail (OEM #ACDelco PT2618 (13580230)) — If the wiring is damaged right at the connector, splicing in a new pigtail is the standard repair.
  Trusted brands: ACDelco, Dorman, Standard Motor Products
  OEM price range: $25-$50
  Aftermarket price range: $15-$30
• Fuel Injector (OEM #12638530 (superseded by 12669384)) — If the wiring is intact, the injector itself is the next most likely component 🎬 Watch: A step-by-step guide to fuel injector replacement. to have failed electrically.
  Trusted brands: ACDelco, Bosch, Standard Motor Products
  OEM price range: $70-$120
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• P0306 — This code means 'Cylinder 6 Misfire Detected'. It is a direct result of the P0276 fault, as the injector circuit problem prevents proper fueling, causing the cylinder to misfire.
• P0206 — This code means 'Injector Circuit/Open - Cylinder 6'. It is another code related to the cylinder 6 injector circuit and can appear alongside P0276 depending on the specific nature of the electrical fault (e.g., a completely broken wire vs. a short to ground).

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: SES Light And Misfire With Injector Codes. Advises inspection of the fuel injector wiring harness for rub-through or internal opens. This TSB applies to a wide range of 2009-2014 GM vehicles with the HFV6 engine family.

Platform-Specific Known Issues

• TSB #PIP4924D: This is the most significant issue for this code on this vehicle. It explicitly states that various injector codes, including P0276, can be caused by the fuel injector wiring harness rubbing through or having an internal wire open. It advises technicians to carefully inspect the harness for damage against the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (2012-2014 3.6L LFX V6) — expected: 1.2 - 1.8 Ohms. Failure: A reading of OL (open circuit), near zero (short circuit), or otherwise outside the specified range indicates a failed injector coil.
• Fuel Injector Resistance (2009-2011 3.0L LF1 / 3.6L LLT V6) — expected: Approximately 12 Ohms. Failure: A significant deviation from 12 Ohms, an open circuit, or a short circuit indicates a failed high-impedance injector.
• Injector Pulse Width at Idle (Live Scan Data) — expected: 2 - 4 milliseconds (ms). Failure: A value of 0 ms for cylinder 6 while other cylinders show normal pulse width suggests the PCM is not commanding the injector, pointing to a wiring or PCM driver issue.
• Injector Circuit Voltage Spike (Oscilloscope) — expected: 60 - 80 Volts. Failure: The absence of this sharp voltage spike when the injector coil's magnetic field collapses indicates an issue in the circuit or with the injector coil itself.

Scan Tool Commands That Help

• GDS2 (GM Factory Scan Tool): Fuel Injector Balance Test — Use this bidirectional command when the injector wiring and resistance tests are inconclusive. The tool commands the injector to fire and measures the resulting drop in fuel rail pressure. A minimal or no pressure drop for cylinder 6 compared to others confirms a functionally faulty (e.g., clogged) or electrically weak injector.

Wiring & Ground Locations

• Cylinder 6 Location — On the transverse V6 engine, this is the cylinder on the front bank (closest to the radiator) on the driver's side of the vehicle.. Correctly identifying the cylinder is the first step to physically inspecting the correct injector, connector, and wiring section.
• G123 (Bank 2 Ground) — Located on the left front corner of the engine cylinder head, near the high-pressure fuel pump.. This is the primary ground for the ignition coils on bank 2 (cylinders 2, 4, 6). While not the injector ground, a loose or corroded ground in this area can introduce electrical noise and intermittent issues to nearby circuits, including the injector harness.
• Injector Power and Control Wires — In the harness running to the fuel injector connector.. On the direct injection engines (LLT/LFX), the ECM uses both a high-side and a low-side driver to control the injector. In many cases, the high-side driver wires have a white tracer. Both wires must be tested for continuity and shorts to ground back to the ECM.

Real Owner Repair Stories

• YouTube channel 's-h-i-t-g-a-r-a-g-e' (2012 Chevrolet Impala with 3.6L LFX engine (same engine family)) — Horrible misfire and code P0276 that would only occur in snowy or wet weather.
  ❌ Tried (didn't work) The owner went straight for a comprehensive repair rather than piecemeal diagnosis due to the intermittent, weather-related nature of the fault.
  ✅ What actually fixed it The owner performed a full intake manifold removal, cleaned the intake valves, and replaced all six fuel injectors and at least one injector harness connector pigtail. He suspected the root cause was the wiring harness or connector for cylinder 6, which was allowing moisture intrusion and causing a short only when wet.

OEM Part Supersession History

• 12638530 → 12669384 — Standard part revision and update by the manufacturer.
  Heads up: It is strongly recommended not to mix aftermarket injectors with OEM (or remanufactured OEM) injectors. Differences in flow rate and atomization can cause fuel trim imbalances between cylinders. If using aftermarket parts, replace all six injectors as a set.

Model Year Variations Within This Range

• 2009-2011 (3.0L LF1 & 3.6L LLT engines): These earlier models use high-impedance fuel injectors with a resistance of approximately 12 Ohms. They also feature an aluminum intake manifold and a Bosch Engine Control Module (ECM).
• 2012-2014 (3.6L LFX engine): The updated LFX engine uses low-resistance direct injectors (1.2 - 1.8 Ohms), a lighter composite intake manifold, cylinder heads with integrated exhaust manifolds, and a Delphi ECM. Using the wrong resistance specification during diagnosis will lead to an incorrect conclusion.