P0264 on 2009-2016 Buick LaCrosse: Cylinder 2 Injector Circuit Low Causes and Fixes

What's Unique About the 2009-2016 Buick LACROSSE

For this generation of Buick LaCrosse, particularly those with the 3.0L (LF1) and 3.6L (LLT, LFX) V6 engines, the fuel injector wiring harness is a known weak point. General Motors issued Technical Service Bulletin (TSB) #PIP4924D specifically because these harnesses are prone to rubbing against engine components like the intake plenum, valve cover bolts, fuel lines, or the side of the cylinder head. This chafing can expose the copper wire, causing it to short to the engine ground, which results in the "low circuit" condition. This makes a thorough wiring inspection the most critical first step, ahead of replacing the injector itself.

Diagnostic Flowchart

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

Generation note: The 2009 model year is the final year of the first-generation LaCrosse, while 2010-2016 models are the second generation. Both generations offered V6 engines (like the 3.0L and 3.6L) where this code is relevant. The primary cause, a chafed wiring harness as described in TSB PIP4924D, applies to both generations equipped with these V6 engines. A key difference is the V6 engine update in 2012 from the LLT to the LFX, which involved different ECMs (Bosch vs. Delphi) and incompatible fuel injectors.

Symptoms You May Notice

• Check Engine Light is on
• Rough or shaking idle
• Engine misfire (may be felt as a shudder)
🎬 Watch: Why some GM 3.6L misfires don't trigger a light.
• Reduced engine power and hesitation during acceleration
• Poor fuel economy
• Engine may stall

Most Likely Causes

1. Fuel Injector Wiring Harness Chafed or Damaged 🔴 High Probability → Shop Engine Wiring Harness As documented in GM TSB #PIP4924D, the injector wiring harness is often routed in a way that it can rub against the intake plenum, valve cover bolts, fuel lines, and on the side of the cylinder head under the plenum. This constant vibration and contact wears through the protective loom and wire insulation, causing a short to ground.
   How to confirm: Visually inspect the entire fuel injector harness, especially the section for cylinder #2 (middle cylinder on the front bank). Pay close attention to where the harness makes contact with other engine parts. A wiggle test on the harness while the engine is running may trigger the fault or cause a change in engine idle. Use a multimeter to check for continuity to ground on the control wire between the PCM and the injector connector; resistance should be less than 1.0 Ohm to the correct pin at the PCM and infinite (OL) to ground.
   Typical fix: Repair the damaged section of the wire with a new piece of wire and solder, and protect it with heat-shrink tubing. If the damage is extensive or in multiple places, replacing the entire injector harness pigtail or sub-harness is recommended. After repair, wrap the harness in high-temperature, anti-abrasion tape (like Tesa tape) and use zip ties to secure it away from sharp edges or hot surfaces.
   Est. part cost: $10-$30 for wire repair supplies, $150-$300 for a new harness
2. Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: After confirming the wiring is intact, swap the cylinder #2 fuel injector with an injector from another cylinder (e.g., cylinder #4). Clear the codes and drive the vehicle. If the code changes to P0270 (Cylinder 4 Injector Circuit Low), the injector is faulty. You can also test the injector's internal resistance with a multimeter. For the direct injection V6 engines (LLT, LFX), the resistance is very low, typically 1.5 to 2.3 ohms. An out-of-spec reading or a reading of 0.0 ohms (short) or OL (open) indicates a bad injector.
   Typical fix: Replace the faulty fuel injector. It is often recommended to replace the Teflon seal and O-rings at the same time. It's best practice to replace all injectors as a set 🎬 See this detailed walkthrough for LFX engine fuel injector replacement. if they are original and high-mileage.
   Est. part cost: $50-$160 per injector
3. Powertrain Control Module (PCM) Failure ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This should be the last resort after all wiring and the injector itself have been proven to be good. A professional shop can use an advanced scan tool like a GM GDS2 to command an injector driver self-diagnostic test or an injector balance test. If the PCM cannot command the injector or reports an internal driver fault, the module is the likely cause.
   Typical fix: Replace and reprogram the Powertrain Control Module. This typically requires a professional with specialized programming tools to match the new PCM to the vehicle's VIN and security system.
   Est. part cost: $300-$800

Rare But Worth Checking

• Corroded or Loose Injector Connector: The electrical connector at the fuel injector itself can become corroded or loose, causing a poor connection. Always check this for bent pins, moisture, or corrosion before performing more complex diagnostics.
• Blown 'EVEN INJ/COIL' Fuse: In some GM vehicles, a severe short in the circuit for one of the even-numbered cylinders (2, 4, 6) can blow a shared fuse, causing all even-numbered cylinders to lose injector and coil function simultaneously. This would result in multiple codes (e.g., P0264, P0270, P0276) and a no-start or extremely rough running condition.
• Loose or Corroded Engine Ground: The ECM and injector driver circuits rely on clean engine grounds, often designated G102, G103, or G104, which are typically bolted to the rear of the cylinder heads or the engine block. A loose or corroded ground can create a voltage drop, causing intermittent and difficult-to-diagnose injector circuit codes.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner and note any other codes present.
2. Visually inspect the fuel injector wiring harness for cylinder #2. Look for chafing, melting, or corrosion, especially where it contacts the intake manifold, valve covers, and fuel lines, as per TSB PIP4924D.
3. Inspect the electrical connector at the cylinder #2 fuel injector for loose connections, bent pins, or corrosion.
4. Use a noid light to test for a signal at the injector connector. The light should flash steadily while the engine is cranking or running, indicating the PCM is sending a signal. A lack of a flash points to a wiring or PCM issue.
5. If the noid light does not flash, check for continuity and shorts to ground on the control wire between the PCM and the injector connector using a multimeter.
6. If the wiring and signal are good, test the fuel injector's resistance with a multimeter. Disconnect the injector and measure across its two pins. A reading outside the specific 1.5-2.3 ohm range for these GDI engines suggests a bad injector.
7. As a final confirmation, swap the cylinder #2 injector with one from another cylinder (e.g., cylinder 4). Clear the codes. If the fault code moves to P0270 (Cylinder 4), the injector is confirmed to be faulty.
8. If all of the above steps fail to identify the issue, the problem may lie within the PCM's injector driver circuit, which requires professional diagnosis.

Parts You'll Likely Need

• Fuel Injector (OEM #12638530 (For 3.6L LLT engine, typically 2009-2011 models, verify with VIN)) — If the injector itself has failed (shorted internally), it will cause a low circuit voltage condition.
  Trusted brands: ACDelco (Genuine GM), Bosch, Standard Motor Products
  OEM price range: $90-$160
  Aftermarket price range: $50-$100
• Fuel Injector Wiring Harness (OEM #12621095 (For 3.6L LLT, verify with VIN)) — This is a very common point of failure on this platform due to chafing and rubbing against engine components, as identified in TSB PIP4924D.
  Trusted brands: ACDelco (Genuine GM), Dorman, TRQ
  OEM price range: $200-$300
  Aftermarket price range: $150-$250
• Fuel Injector Connector Pigtail — If only the connector or the wire immediately attached to it is damaged, a pigtail can be spliced in, which is much cheaper than replacing the whole harness.
  Trusted brands: ACDelco, Dorman, Standard Motor Products (S-824)
  OEM price range: $25-$40
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• P0302 — P0302 means "Cylinder 2 Misfire Detected." Since P0264 indicates a problem with the fuel supply to cylinder 2, a misfire in that same cylinder is a direct consequence.
• P0202 — P0202 is a more general "Cylinder 2 Injector Circuit Malfunction." It often appears with P0264 as they both point to an electrical fault in the same circuit.
• P0261, P0267, P0270, etc. — If multiple injector circuit codes (low or high) appear for different cylinders, it strongly points to a widespread wiring harness issue or a problem with the PCM's injector driver banks, as described in TSB PIP4924D.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: SES Light And Misfire With Injector Codes. This TSB points to the fuel injector wiring harness rubbing through as a common cause for P0264 and related codes.

Platform-Specific Known Issues

• TSB PIP4924D: General Motors issued this bulletin for a wide range of vehicles, including the 2009-2014 LaCrosse with V6 engines, due to misfires and various injector codes (including P0264). The bulletin directs technicians to carefully inspect the fuel injector wiring harness for rubbing against the intake plenum, at valve cover bolts, against the fuel line and on the side of the head under the plenum, and to repair or replace the harness as needed.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance (3.6L LFX Engine) — expected: 1.9-2.3 Ohms at 20°C (68°F). Failure: A reading of 0.0 Ohms (short), OL (open), or significantly outside the specified range.
• Fuel Injector Coil Resistance (3.6L LLT Engine) — expected: ~1.5 Ohms. Failure: A reading significantly different from the other injectors on the engine.
• Injector Control Circuit Voltage (Key On, Engine Off) — expected: Close to 5.0 Volts when back-probed at the PCM connector.. Failure: A reading below 4.5 Volts suggests a short to ground or high resistance in the harness.
• Injector Wiring Harness Continuity — expected: Under 1.0 Ohm from the injector connector to the corresponding ECM connector pin.. Failure: Resistance above 1.0 Ohm indicates corrosion or a damaged wire.

Scan Tool Commands That Help

• GM GDS2 / Tech2: Fuel Injector Balance Test — This special function pulses each injector for a precise duration and measures the corresponding drop in fuel rail pressure. It can identify a clogged or weak injector that may not have a hard electrical fault but is causing performance issues. It's a definitive test before physically removing injectors.
• GM GDS2 / Tech2: Cylinder Power Balance — Used to confirm a misfire on a specific cylinder when P0302 is also present. The tool deactivates one injector at a time and measures the RPM drop. If disabling cylinder #2 causes little or no change in RPM, it confirms that cylinder is not contributing power.
• GM GDS2 / Tech2: AFIT (Active Fuel Injector Tester) — On vehicles that support it, this is an automated dealer-level function that performs a comprehensive electronic and pressure-based test to check for electrical faults, leaks, and flow restrictions without removing the injectors.

Wiring & Ground Locations

• G102 / G103 / G104 — Commonly located on the rear of the cylinder heads or on the engine block itself. For example, G103 is sometimes noted as a redundant ground from the ECM to the even bank cylinder head.. The ECM's injector driver circuits require a stable and clean ground reference. A loose, corroded, or broken ground at these primary engine points can cause voltage drops and electrical noise, leading to false or intermittent injector circuit codes like P0264.
• ECM Connector (X1/X2) — The Engine Control Module is typically located in the engine bay, against the firewall or on a fender apron. The injector control wires are in the large multi-pin connectors (often X1 or X2).. To definitively rule out a wiring problem, a technician must perform continuity and short-to-ground tests from the injector's connector all the way back to the specific pin at the ECM connector. This isolates the fault to the harness, injector, or ECM.
• Cylinder #2 Location — On the transverse mounted 3.0L and 3.6L V6 engines, Cylinder 2 is the middle cylinder on the front bank (the bank closest to the radiator).. Correctly identifying cylinder #2 is the first step in any physical diagnosis, such as inspecting the wiring, testing the connector, or swapping the injector.

Real Owner Repair Stories

• ScannerDanner Forum (2011 Buick LaCrosse 3.6L V6) — Misfire on cylinders 3, 4, and 6 with code P1255. ECM was not supplying power/ground to the injectors.
  ❌ Tried (didn't work) Cleaning all injectors, Performing resistance tests on all injectors
  ✅ What actually fixed it The problem was confirmed to be the ECM not firing the injectors. A new ECM was ordered and resolved the issue.

OEM Part Supersession History

• 12611545, 12632255 → 12638530, which is now superseded by 12669384 — Manufacturer part consolidation and design revisions.
  Heads up: These injectors are for the LLT engine and are NOT compatible with the 2012+ LFX engine, which uses a different injector (e.g., 12634126).

Model Year Variations Within This Range

• 2009-2011: These models primarily used the 3.0L LF1 or 3.6L LLT V6 engines. These engines use a Bosch ECM, have external/separate exhaust manifolds, and use fuel injector part number 12638530 (or its supersessions) for the 3.6L.
• 2012-2016: Starting in 2012, the primary V6 was the updated 3.6L LFX. This engine features cylinder heads with integrated exhaust manifolds, a composite (plastic) intake manifold, and uses a Delphi ECM. The injectors, wiring harness, and ECM are different and not interchangeable with the earlier LLT engine.