P0262 on 2009-2014 Buick LaCrosse: Cylinder 1 Injector Circuit High

What's Unique About the 2009-2014 Buick LACROSSE

For this generation of Buick LaCrosse and other GM vehicles from the era, a known issue is the fuel injector wiring harness. A Technical Service Bulletin (TSB #PIP4924D) was issued for a wide range of injector codes, including P0262, pointing 🎬 Watch: Understanding the P0262 code and circuit high symptoms. technicians to inspect the harness for chafing or internal wire breaks. The TSB specifically mentions to check for rubbing against the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head under the plenum, making these key areas to inspect before replacing parts. This suggests that before replacing the injector itself, a thorough inspection of the wiring harness is critical, as it's a documented weak point on this platform.

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 (2009) and the majority of the second generation (2010-2014) of the Buick LaCrosse. The provided TSB applies to models starting from 2009, indicating the potential for wiring issues exists across this year span. Engines offered included the 2.4L 4-cylinder, 3.0L V6, and 3.6L V6. For the V6 engines, cylinder 1 is the front-most cylinder on the cylinder bank closer to the firewall (rear bank). The P0262 code's diagnosis is similar for all engines, but part numbers and specific harness routing will vary.

Symptoms You May Notice

• Check Engine Light is on
• Rough idle or engine stumbling
• Engine misfire, which may feel like a popping or hesitation
• Loss of power and poor acceleration
• Increased fuel consumption and poor fuel economy
• Strong fuel smell from the exhaust or engine bay
• Black smoke from the exhaust

Most Likely Causes

1. Fuel Injector Wiring Harness or Connector Issue 🔴 High Probability → Shop Engine Wiring Harness A GM Technical Service Bulletin (PIP4924D) specifically calls out inspecting the fuel injector wiring harness for rubbing or internal breaks when a wide array of injector codes, including P0262, are present. Common chafe points are against the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head. Engine vibration over time wears through the wire insulation, causing a short to voltage.
   How to confirm: Visually inspect the wiring harness leading to the cylinder 1 fuel injector for any signs of chafing, melting, or damage, especially in the areas mentioned in TSB PIP4924D. Check the connector for corrosion, bent pins, or a loose fit. Use a multimeter to check for a short to voltage in the signal wire between the PCM and the injector connector.
   Typical fix: Repair the damaged section of the wiring harness or replace the injector connector pigtail. Use heat shrink tubing to protect the repair.
   Est. part cost: $15-$50
2. Faulty Cylinder 1 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector Fuel injectors can fail over time. An internal short circuit in the injector's coil can cause a high voltage reading. The 3.6L LFX V6 engine, in particular, uses direct injection, and these high-pressure injectors can be a failure point leading to misfires and fuel-related codes.
   How to confirm: Use a multimeter to test the resistance of the fuel injector. Disconnect the injector and measure across its two pins. Compare the reading to the manufacturer's specification (typically between 11-14 ohms for standard injectors). A reading significantly lower than spec or showing a short indicates a bad injector. Another method is to swap the cylinder 1 injector with another cylinder's injector (e.g., cylinder 3). Clear the codes and drive. If the trouble code follows to the new cylinder (e.g., P0268 for cylinder 3), the injector is confirmed faulty.
   Typical fix: Replace the faulty fuel injector. On V6 models, it is often recommended to replace all injectors on that bank at the same time, especially for high-mileage vehicles. For direct injection engines (like the 3.6L), this is a more involved job.
   Est. part cost: $70-$200
3. Faulty Powertrain Control Module (PCM) ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This should be the last step after confirming the injector and wiring are good. A professional shop would use advanced diagnostic tools to verify the injector driver circuit within the PCM is faulty. This is a rare failure.
   Typical fix: Replace and reprogram the Powertrain Control Module. The new PCM must be programmed with the vehicle's specific VIN and software.
   Est. part cost: $300-$800

Diagnosis Steps

1. Scan the vehicle for all DTCs. Note any other codes present, especially misfire codes (P0301) or other injector codes.
2. Carefully inspect the wiring harness and connector for cylinder 1's fuel injector. Per TSB PIP4924D, pay close attention to areas where the harness might rub against the intake, valve cover, or cylinder head.
3. With the key on and engine off, use a multimeter to check for voltage at the injector connector. You should see battery voltage on the power wire.
4. Disconnect the injector and measure its internal resistance with a multimeter. Compare the reading to the vehicle's specifications (e.g., 11-14 ohms). A very low or zero-ohm reading indicates a shorted injector.
5. If you have a 'noid light' tester, connect it to the injector harness and start the engine. The light should flash steadily. If it stays on solid, this indicates a short to power in the control circuit.
6. If the injector and wiring appear good, swap the cylinder 1 injector with one from another cylinder (e.g., cylinder 3). Clear the codes and drive the vehicle. If the code returns for the cylinder you moved the injector to (now P0268), the injector is faulty.
7. If the code remains on cylinder 1 (P0262) after the swap, the problem is definitively in the wiring harness or the PCM's driver circuit.

Parts You'll Likely Need

• Fuel Injector (OEM #12638530 (For 3.6L LLT V6, 2010-2011), 12669384 (supercedes 12638530), 12634126 (For 3.6L LFX V6, 2012-2014)) — An internal short in the injector is a common cause for this high voltage code.
  Trusted brands: ACDelco, Bosch, Delphi
  OEM price range: $120-$200
  Aftermarket price range: $70-$150
• Fuel Injector Connector Pigtail (OEM #13576411 (ACDelco)) — The connector itself can become corroded or the wires can break right at the connector from vibration and heat, causing a short to voltage. This is a common repair when the harness is damaged near the injector.
  Trusted brands: ACDelco, Dorman
  OEM price range: $25-$40
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• P0301 — P0301 is a misfire code for cylinder 1. Since P0262 causes a fueling problem in cylinder 1 (either too much fuel from being stuck open or no fuel if the PCM shuts it down), it will almost always be accompanied by a misfire.
• P0261 — P0261 is 'Cylinder 1 Injector Circuit Low'. Seeing both high and low circuit codes intermittently can strongly indicate an intermittent wiring short or a failing PCM driver.
• P0201 — P0201 is a general 'Injector Circuit/Open' code for cylinder 1. It can appear alongside P0262 if the nature of the electrical fault changes or if the PCM is trying to isolate the problematic circuit.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Addresses a Service Engine Soon light and misfire with multiple injector DTCs (including P0262), advising inspection of the fuel injector wiring harness for damage at specific chafe points.

Platform-Specific Known Issues

• Technical Service Bulletin PIP4924D was issued by GM for multiple vehicles, including the 2009-2014 LaCrosse, for a variety of fuel injector codes. It advises technicians to inspect the fuel injector wiring harness for chafing against the intake plenum, valve cover bolts, fuel lines, and the side of the head under the plenum. This indicates a known failure point that should be checked first.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (3.6L LLT V6, 2010-2011) — expected: 1.5 - 1.6 Ohms. Failure: A reading significantly outside this range, or showing an open (OL) or shorted (near 0 Ohms) circuit.
• Fuel Injector Resistance (3.6L LFX V6, 2012-2014) — expected: 1.2 - 1.8 Ohms or 1.9 - 2.3 Ohms at 68°F (20°C). Failure: A reading outside the specified range indicates a failed injector. Resistance changes with temperature.
• Injector Pulse Width (at idle, warmed up) — expected: 2 - 4 milliseconds (ms). Failure: A value of 0 ms on cylinder 1 while others are pulsing indicates the ECM has disabled the injector.
• Injector Control Circuit Voltage (Key On, Engine Off, Injector Disconnected) — expected: 0 Volts on the control wire. Failure: Any voltage, especially battery voltage, indicates a short to power in the harness.

Scan Tool Commands That Help

• GM GDS2: Injector Balance Test — This is an automated test used when wiring and resistance tests are inconclusive. The tool commands each injector to fire and measures the corresponding drop in fuel rail pressure. A minimal or no pressure drop for cylinder 1 compared to others points to a faulty injector or a circuit issue that prevents it from firing.
• Professional Bidirectional Scan Tool: Cylinder Power Balance / Injector Kill — This function allows the user to manually disable individual injectors. When a good cylinder's injector is disabled, engine RPM will drop. If disabling cylinder 1 causes no change in RPM, it confirms that cylinder was not contributing to begin with, pointing to a fault in that circuit.

Wiring & Ground Locations

• G102 / G104 — Commonly located on the rear of the cylinder heads, bolted directly to the engine block.. These are major engine ground points. A poor or corroded ground at these locations can cause a host of electrical issues and erratic behavior in sensor and actuator circuits, including the fuel injectors.
• ECM X1 Connector — The main engine-side connector at the Engine Control Module (ECM), located in the engine bay.. The control and supply voltage circuits for all fuel injectors run through this connector. For a 3.6L engine, the Cylinder 1 Injector Control circuit is on a specific pin (e.g., Pin 74, Tan wire on some models). Testing for signal and continuity at this pin can confirm if the ECM is sending a signal and if the wiring is intact back to the injector.
• TSB PI1067 Chafe Point — On 2013-2014 models with the 3.6L LFX engine, where the ECM wiring harness (from connector X1) can rub on the metal ECM bracket.. This is a specific, documented chafe point that can cause shorts or opens in any of the circuits passing through that part of the harness, including the injector circuits.

OEM Part Supersession History

• 12638530 → 12669384 — Standard part update/revision by GM.
  Heads up: Part #12638530 is for the earlier 3.6L LLT direct injection engine (approx. 2010-2011). Part #12669384 is for the later 3.6L LFX engine (approx. 2012-2014). They have different resistance values and are not interchangeable. Using the wrong injector can cause performance issues and codes.

Model Year Variations Within This Range

• 2009-2011: These models primarily used the 3.0L LF1 or 3.6L LLT V6 engines. The LLT engine uses a Bosch ECM, has external exhaust manifolds, and its injectors (PN 12638530) have a resistance of about 1.5-1.6 Ohms.
• 2012-2014: These models used the updated 3.6L LFX V6. This engine features cylinder heads with integrated exhaust manifolds, a composite intake manifold, and uses a Delphi ECM. The injectors (PN 12669384) have a different resistance (1.2-1.8 or 1.9-2.3 Ohms). The wiring harnesses and ECM are not interchangeable with the earlier LLT engine.