P0273 on 2012-2014 Chevrolet Impala: Cylinder 5 Injector Circuit Low Causes and Fixes

What's Unique About the 2012-2014 Chevrolet IMPALA

For this generation of Impala and other GM vehicles using the 3.6L LFX V6 engine, the fuel injector wiring harness is notoriously prone to damage. GM issued Technical Service Bulletin #PIP4924D specifically because this harness can rub against the intake manifold, cylinder head, fuel lines, or valve cover bolts, causing wires to break or short out. This makes a wiring issue a much higher probability than a failed injector itself, which is a key difference from how this code might be approached on other vehicles.

Diagnostic Flowchart

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

Generation note: The 2012-2013 Impala belongs to the ninth generation (W-body). The 2014 model year introduced the tenth generation, but the ninth generation was also sold as the 'Impala Limited' for fleet sales. This guide applies to all 2012-2014 models equipped with the 3.6L V6 engine, as the P0273 code refers to cylinder #5, which 4-cylinder models do not have. The primary cause (wiring harness chafe) is common to the 3.6L V6 across both generations and many other GM vehicles.

Symptoms You May Notice

• Check Engine Light is on
• Engine running rough or vibrating (misfire)
• Reduced engine power and poor acceleration
• Engine hesitation or stumbling
• Decreased fuel economy
• A distinct fuel smell from the exhaust
• Engine may be difficult to start or stall intermittently

Most Likely Causes

1. Chafed or Damaged Fuel Injector Wiring Harness 🔴 High Probability → Shop Engine Wiring Harness As documented in GM TSB #PIP4924D, the engine wiring harness is routed in a way that it frequently rubs against the intake plenum, valve cover bolts, or the side of the cylinder head, causing wires to short out. This is a widespread issue across many GM models with the 3.6L engine.
   How to confirm: Visually inspect the entire fuel injector wiring harness, especially on the firewall side of the engine (Bank 1) where cylinder 5 is located. Look for bare wires, melted plastic loom, or shiny rub marks where the harness contacts the intake manifold, fuel lines, EVAP purge solenoid bracket, or cylinder head. The damage is often on the underside of the harness and not immediately visible. Wiggling the harness with the engine running may cause the misfire to change or disappear, confirming a wiring fault.
   Typical fix: Repair the damaged section of wire with a weatherproof butt connector or by soldering and using heat-shrink tubing. Protect the repaired area with new wire loom or high-temperature tape and secure it away from the component it was rubbing against. If damage is near the connector, a new pigtail (e.g., ACDelco PT2160) may be needed.
   Est. part cost: $10-$40
2. Faulty Cylinder 5 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector While less common than the wiring issue, the direct fuel injector can fail internally from an electrical fault (open or shorted coil). These are high-pressure components that operate in a harsh environment.
   How to confirm: Disconnect the injector and measure its resistance with a multimeter. For the LFX engine, the specification is approximately 1.2-1.8 Ohms. A reading of 'OL' (open) or near zero ohms indicates a bad injector. The most definitive test is to swap the cylinder 5 injector with another one (e.g., cylinder 3). Clear the codes and run the engine. If the code moves to P0267 (Cylinder 3 Injector Circuit Low), the injector is confirmed bad.
   Typical fix: Replace the faulty fuel injector. Accessing the injectors requires removing the upper intake manifold, so you will also need to replace the intake manifold gaskets. It is often recommended to replace all three injectors on the same bank at the same time.
   Est. part cost: $70-$150

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare. The internal driver circuit for the injector can fail. This should only be considered after the wiring and injector have been definitively ruled out as the cause. All other possibilities must be exhausted first.
• Loose or Corroded Injector Connector: Vibration can cause the pins in the electrical connector at the injector to become loose or corroded, creating a poor connection. Always check for clean and tight pins when diagnosing. The connector locking tab can also become brittle and break.

Diagnosis Steps

1. Scan the vehicle for all stored trouble codes. Note P0273 and any other codes, especially P0305 or other injector circuit codes.
2. Perform a thorough visual inspection of the fuel injector wiring harness as described in TSB #PIP4924D. Pay close attention to areas where it might rub against the engine, intake manifold, fuel lines, or valve cover bolts. This is the most critical step.
3. If no visible damage is found, disconnect the electrical connector at the cylinder 5 fuel injector. Check for corrosion or loose pins.
4. Use a noid light to test the signal at the injector connector. The light should flash while the engine is cranking or running, indicating the PCM is sending a signal.
5. With the ignition off, use a multimeter to measure the resistance across the two terminals of the fuel injector. A good LFX injector should read between 1.2 and 1.8 ohms. A significantly different reading, or an open (OL) or shorted (0 ohms) circuit, means the injector is bad.
6. If the injector tests good, perform an injector swap with an adjacent cylinder as a final confirmation. If the code follows the injector, the injector is faulty. If the P0273 code returns, the problem is in the wiring or PCM.
7. If the wiring and injector are confirmed to be good, the final and least likely possibility is a faulty PCM driver circuit.

Parts You'll Likely Need

• Fuel Injector Wiring Harness Repair materials — This is the most common fix due to the known chafing issue described in TSB #PIP4924D. Often only a small section of wire needs repair.
  Trusted brands: 3M, Tesa
  OEM price range: $10-$30 (for repair materials)
  Aftermarket price range: $10-$30 (for repair materials)
• Fuel Injector (OEM #ACDelco 12669384 (supersedes 12638530, 12632255, 12611545)) — If the injector itself has failed with an internal short or open circuit, it will need to be replaced. This is the second most likely cause.
  Trusted brands: ACDelco, Bosch, Delphi
  OEM price range: $100-$180
  Aftermarket price range: $50-$120
• Upper Intake Manifold Gasket Set (OEM #Fel-Pro MS 97204) — These are single-use gaskets that must be replaced anytime the intake manifold is removed to access the fuel injectors.
  Trusted brands: Fel-Pro, ACDelco
  OEM price range: $30-$50
  Aftermarket price range: $20-$40
• Fuel Injector Connector Pigtail (OEM #ACDelco PT2160) — If the wiring is damaged right at the connector, or the connector's locking tab is broken, replacing the pigtail is the standard repair.
  Trusted brands: ACDelco, Dorman
  OEM price range: $25-$40
  Aftermarket price range: $10-$25

Related Codes That Often Appear With This One

• P0305 — P0305 means 'Cylinder 5 Misfire Detected'. Since P0273 indicates a problem with the fuel supply to cylinder 5, a misfire is the direct result and this code is almost always present as well.
• P0205, P0261, P0264, etc. — If other injector circuit codes for different cylinders appear simultaneously, it strongly points to a widespread wiring harness issue affecting multiple wires, as described in TSB #PIP4924D.
• P219A — This code indicates 'Bank 1 Air-Fuel Ratio Imbalance'. Since cylinder 5 is in Bank 1, a malfunctioning injector can cause the entire bank's fuel trim to be skewed, triggering this code.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Warns of engine misfires and various injector circuit codes (including P0273) caused by the fuel injector wiring harness rubbing through on engine components like the intake, valve covers, fuel lines, or the side of the cylinder head. This TSB applies to a wide range of 2009-2014 GM vehicles with 3.0L and 3.6L engines.

Platform-Specific Known Issues

• A widespread and well-documented issue with the fuel injector wiring harness rubbing through on engine components is the primary cause for this code, as outlined in GM Technical Service Bulletin #PIP4924D.
• Owner experiences shared on forums frequently confirm that replacing the injector does not fix the problem, but a subsequent inspection reveals a chafed wire that, once repaired, resolves the code.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance — expected: 1.2 - 1.8 Ohms when tested at the injector terminals.. Failure: A reading near 0 Ohms indicates a shorted coil, while an infinite (OL) reading indicates an open coil. Any reading significantly outside the expected range points to a faulty injector.
• Injector Pulse Width (Scan Tool) — expected: 2 - 4 milliseconds (ms) at idle on a warm engine.. Failure: A value of 0 ms for cylinder 5 while other cylinders show a normal pulse width indicates the ECM is not commanding the injector, pointing to a wiring or ECM driver issue.
• Injector Circuit Voltage (at connector) — expected: One wire should show battery voltage (~12V) with Key On, Engine Off. The other wire is the control, which the ECM pulses to ground.. Failure: No voltage on the power wire indicates a problem upstream (fuse, relay, or harness). A control wire that is constantly grounded indicates a short in the harness or a failed ECM driver.
• Injector Balance Test (Pressure Drop) — expected: The fuel rail pressure drop for each injector should be within 1.5 PSI of the average of all cylinders.. Failure: An injector with a pressure drop significantly different from the others is likely clogged, leaking, or mechanically faulty.

Scan Tool Commands That Help

• GM GDS2 / Tech2 or equivalent professional scanner: Fuel Injector Balance Test — This is the primary functional test to use after a visual wiring inspection and electrical tests (resistance, noid light) are inconclusive. It commands each injector to fire and measures the corresponding fuel pressure drop, which can identify a mechanically faulty (clogged, sticking) or underperforming injector that electrical tests would miss.
• GM GDS2 / Tech2 or equivalent professional scanner: Cylinder Power Balance — This function helps confirm that cylinder 5 is not contributing power, which is expected with a P0273 code. The tool sequentially disables fuel to each cylinder and measures the drop in RPM. If disabling cylinder 5 causes little or no change in RPM, it confirms the misfire is on that cylinder.

Wiring & Ground Locations

• Cylinder 5 Injector Circuit at ECM — Pins 28 (Light Green) and 29 (Light Green/White) on the X1 connector of the Engine Control Module (ECM).. These are the specific pins for the cylinder 5 injector high and low side drivers. Testing for continuity and shorts between these pins and the injector connector is the definitive way to diagnose the wiring harness.
• ECM Connector X1 — Of the three main connectors on the LFX ECM, X1 is identifiable by its Blue (BU) Terminal Position Assurance (TPA) lock/lever.. Correctly identifying the X1 connector is essential before attempting to probe pins 28 and 29 for diagnosis, preventing potential damage to other circuits.
• Engine Block Ground G111 — Typically located on the engine block, above the starter motor.. A poor engine ground can cause a variety of electrical issues, including erratic sensor and actuator behavior. While not a direct cause of a single injector circuit code, ensuring this ground is clean and tight is a good practice during any electrical diagnosis.
• Common Harness Chafe Point — The wiring harness on the firewall side of the engine (Bank 1) where it can rub against metal brackets, the intake manifold, or valve cover bolts.. This is the most common location for the short-to-ground that triggers P0273, as documented in TSB #PIP4924D. The wire for cylinder 5 is often the victim.

Real Owner Repair Stories

• acadiaforum.net user report (2010 GMC Acadia (platform mate with 3.6L V6)) — Check engine light with codes P0273, P0305, and P0300 (random misfire). Engine had a rough idle and poor performance.
  ❌ Tried (didn't work) Replaced spark plugs and ignition coils., Swapped the cylinder 5 fuel injector with another cylinder's injector.
  ✅ What actually fixed it The owner found the fuel injector wiring harness was rubbing against a metal bracket near the firewall. The insulation on the wire for the cylinder 5 injector had worn through, causing a short to ground. Repairing the wire resolved all codes.
• traverseforum.com user report (Chevrolet Traverse (2009-2014 range) with 3.6L V6) — Check Engine Light with codes P0273 and P0305.
  ❌ Tried (didn't work) Initial diagnosis was inconclusive.
  ✅ What actually fixed it A single wire in the fuel injector harness located on the back of the engine had rubbed through on a metal bracket. Repairing the damaged wire fixed the issue.

OEM Part Supersession History

• 12611545, 12632255, 12638530 → 12669384 — The part has been updated multiple times by GM. The latest part number, 12669384, incorporates design improvements to increase durability and address potential leaking issues found in earlier versions.
  Heads up: While older part numbers may physically fit, it is highly recommended to use the latest superseded part number for any replacement to ensure longevity.

Model Year Variations Within This Range

• 2012-2014: The 3.6L LFX engine used in these model years features redesigned cylinder heads with integrated exhaust manifolds and a lighter composite intake manifold compared to the earlier LLT engine (pre-2012). While the primary cause of P0273 (harness chafing) remains the same, the exact routing of the harness and specific chafe points may differ slightly due to the different head and manifold design.