P0273 on 2010-2015 GMC Terrain V6: Cylinder 5 Injector Circuit Low Causes & Fixes

What's Unique About the 2010-2015 Gmc TERRAIN

For this generation of GMC Terrain and its V6 engines, the P0273 code is very frequently caused by a platform-specific vulnerability. GM issued multiple Technical Service Bulletins (TSBs) warning technicians that the engine wiring harness is prone to rubbing through its protective wrap where it is routed near the back of the engine, valve cover bolts, or fuel lines. This chafing can cause a short to ground in the injector circuit, triggering the code long before the injector itself has failed. This issue is common across many GM vehicles sharing this engine platform.

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 shaky idle
• Engine misfire, which may feel like a shudder or hesitation
• Reduced engine power and poor acceleration
• Decreased fuel economy
• A tapping or popping sound from the engine bay
• Engine may be hard to start or may stall

Most Likely Causes

1. Damaged Fuel Injector Wiring Harness 🔴 High Probability → Shop Engine Wiring Harness As documented in TSBs #PIT5424 and #PIP4924D, the harness routing on this platform makes it susceptible to rubbing against engine components. Common chafe points include the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head under the plenum. This can cause wires for one or more injectors to short to ground.
   How to confirm: Visually inspect the entire length of the fuel injector harness, especially between the ECM and the upper rear of the engine. Look for any signs of abrasion, melting, or exposed wires. Wiggle the harness with the engine running to see if it affects the idle, which can help pinpoint an intermittent short.
   Typical fix: Repair the damaged section of wire and protect it with new conduit or anti-abrasion tape. Re-route or secure the harness with zip ties to prevent future contact with sharp edges. In severe cases, the harness pigtail or the entire injector harness may need replacement.
   Est. part cost: $5-$150
2. Faulty Cylinder 5 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector The fuel injector itself can fail internally, typically from an electrical short in the solenoid winding. While less common than the harness issue on this platform, it is still a frequent failure point for all vehicles as they age.
   How to confirm: Measure the resistance of the fuel injector with a multimeter. For these GDI engines, the expected resistance is low, around 1.5 to 2.0 ohms. Compare the reading to a known good injector on another cylinder. A reading that is significantly lower (shorted) or higher (open) than the others indicates a faulty injector. Alternatively, swap the cylinder 5 injector with another one (e.g., cylinder 3) and see if the trouble code follows to the new cylinder (e.g., P0267).
   Typical fix: Replace the faulty fuel injector. It is recommended to replace the injector O-ring seals at the same time.
   Est. part cost: $40-$120
3. Loose or Corroded Connector ⚪ Low Probability
   How to confirm: Unplug the electrical connector at the cylinder 5 fuel injector and at the ECM (Connector X2, Pin 49 for the LFX engine). Inspect the pins and terminals for any signs of corrosion, moisture, or damage. Ensure the connector fits snugly and the locking tab is secure. Check for proper terminal tension by gently pulling on the wires.
   Typical fix: Clean the connector terminals with electrical contact cleaner. If the connector or pins are damaged, the pigtail may need to be replaced.
   Est. part cost: $10-$30

Rare But Worth Checking

• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This should be the last resort after all other possibilities have been exhausted. The injector driver circuit within the ECM can fail, but it is uncommon. A failed ECM will typically cause other issues and codes as well. Professional diagnosis is recommended before replacement.

Diagnosis Steps

1. Read all stored DTCs with an OBD-II scanner. Note if other injector, misfire, or circuit codes are present, as multiple codes strongly suggest a harness issue.
2. Perform a thorough visual inspection of the engine wiring harness, focusing on the areas highlighted in TSBs #PIT5424 and #PIP4924D: between the ECM and the upper rear of the engine, near valve cover bolts, against the fuel line, and around the intake plenum.
3. Inspect the electrical connector at the cylinder 5 fuel injector for damage, corrosion, or loose pins. Ensure it is securely latched.
4. If the harness and connector appear intact, use a noid light to test for a signal at the injector connector. A flashing light indicates the ECM is attempting to fire the injector.
5. If the noid light test passes, measure the resistance of the fuel injector with a multimeter. A reading near 1.5-2.0 ohms is expected for these GDI engines. A reading near zero ohms indicates a shorted injector. Compare with another cylinder to verify.
6. If injector resistance is good, test the wiring for continuity and shorts. Disconnect the ECM and injector, then check for a short to ground on the control circuit wire between the ECM connector (e.g., X2, Pin 49 on LFX) and the injector connector.
7. If the injector and wiring are confirmed to be good, the final possibility is a fault within the Engine Control Module (ECM), which should be diagnosed by a professional.

Parts You'll Likely Need

• Fuel Injector (OEM #12669384 (supersedes 12638530)) — If the wiring harness is intact, the injector itself is the next most likely component to have failed with an internal short.
  Trusted brands: ACDelco (GM Genuine), Delphi, Bosch
  OEM price range: $70-$110
  Aftermarket price range: $40-$80
• Fuel Injector Connector Pigtail (OEM #12102568 (Interchange)) — If the connector at the injector is damaged or corroded, or if wiring is damaged close to the connector, a new pigtail is needed to make a solid repair.
  Trusted brands: ACDelco, Dorman (e.g., 85139)
  OEM price range: $20-$40
  Aftermarket price range: $10-$25
• Anti-Abrasion Tape or Split Loom Conduit — After repairing a chafed wire, this is essential to protect the repair and prevent the problem from recurring.
  Trusted brands: Tesa, 3M, Dorman
  OEM price range: $5-$15
  Aftermarket price range: $5-$15

Related Codes That Often Appear With This One

• P0305 — P0305 means 'Cylinder 5 Misfire Detected.' A low voltage condition in the injector circuit (P0273) will prevent the injector from delivering the correct amount of fuel, directly causing a misfire in that cylinder.
• P0205 — This is a more general code for 'Cylinder 5 Injector Circuit Malfunction' and is often set along with the more specific P0273.
• P0261, P0264, P0267, P0270, P0276 — These are 'Circuit Low' codes for other cylinders. If they appear with P0273, it strongly points to a widespread wiring harness issue affecting multiple injector circuits, as noted in TSB #PIT5424.
• P0641 — This code for 'Sensor Reference Voltage 'A' Circuit/Open' is also mentioned in TSB #PIT5424 and can be triggered by the same harness shorting issue that causes the injector codes. A short in an injector wire can pull down the entire 5-volt reference circuit it shares, affecting unrelated sensors.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #PIT5424: Addresses multiple injector DTCs, including P0273, caused by engine harness routing issues.
• Bulletin #PIP4924D: Details misfires and injector codes resulting from the fuel injector wiring harness rubbing through on engine components.

Platform-Specific Known Issues

• TSB #PIT5424: Specifically calls out inspecting the engine harness routing between the ECM and the upper rear of the engine for chafing, which can cause P0273 and other injector codes (P0261, P0264, P0267, P0270, P0276) and P0641.
• TSB #PIP4924D: Warns technicians to inspect the fuel injector wiring harness for rubbing through on components like the intake plenum, valve cover bolts, against the fuel line, and on the side of the head under the plenum, leading to a wide range of injector circuit codes including P0273.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance (3.0L & 3.6L GDI engines) — expected: 1.5 to 2.0 Ohms. Failure: A reading of OL (infinity) indicates an open circuit, while a reading near 0 ohms indicates a shorted injector.
• Injector Control Circuit Voltage (Key On, Engine Off) — expected: Should be near battery voltage (~12V). Failure: A low voltage reading on the control wire can indicate a short to ground in the harness, which is the direct cause of a P0273 code.
• Engine Ground to Chassis Continuity — expected: < 1.0 Ohm. Failure: A high resistance reading indicates a poor ground connection, which can cause various electrical issues, including erratic sensor and actuator behavior.

Scan Tool Commands That Help

• GDS2 (GM Techline Connect): Fuel Injector Balance Test — This bidirectional function commands the ECM to pulse each injector for a set duration while monitoring fuel pressure drop. An injector that causes a significantly different pressure drop compared to others is likely faulty. This can confirm a bad injector after wiring has been ruled out.
• GDS2 (GM Techline Connect): Cylinder Power Balance — This function allows the technician to disable one cylinder at a time to observe the corresponding drop in engine RPM. If disabling cylinder 5 causes little or no change in RPM, it confirms that cylinder is not contributing power, which supports the P0273 diagnosis.
• GDS2 (GM Techline Connect): View Injector Circuit Status — When diagnosing, a technician can view the status of the injector circuit as seen by the ECM. With the injector harness disconnected, the status should read 'Open.' If it reads 'OK' or 'Shorted,' it points to a wiring issue between the ECM and the disconnect point.

Wiring & Ground Locations

• Cylinder 5 Injector Connector — Cylinder 5 is the middle cylinder on the front bank (radiator side) of the V6 engine. The connector is on top of the injector, underneath the upper intake manifold.. This is the starting point for diagnosis. The connector itself can be loose or corroded, and the wiring near the connector is susceptible to heat damage and vibration, causing a short or open.
• ECM Connector X2, Pin 49 (for 3.6L LFX) — The Engine Control Module (ECM) is located in the engine bay, near the battery or firewall. X2 is one of the main connectors to the ECM.. This is the specific pin on the ECM that sends the control signal to the cylinder 5 fuel injector. A continuity and short-to-ground test must be performed on the wire running from this pin to the injector connector to rule out a wiring fault.
• G109 / G112 — According to wiring diagrams for the 2014 Terrain, G109 is on the right front of the engine (for 3.6L) and G112 is on the left rear of the engine (for 3.6L). These are primary engine-to-chassis grounds.. The ECM and its sensors/actuators rely on clean ground connections. A loose or corroded engine ground can create a floating voltage potential, causing the ECM to misinterpret circuit voltages and potentially set false codes like P0273.

Real Owner Repair Stories

• traverseforum.com user report (2011 Chevrolet Traverse 3.6L V6 (shared engine and platform)) — Check engine light with multiple injector circuit codes.
  ❌ Tried (didn't work) Dealer replaced the #6 fuel injector.
  ✅ What actually fixed it The owner found and repaired a chafed wire in the fuel injector wiring harness where it was rubbing against an engine component.
• acadiaforum.net user report (2008 GMC Acadia 3.6L V6) — Check Engine Light, rough idle, misfire codes.
  ❌ Tried (didn't work) Replacing spark plugs and ignition coils.
  ✅ What actually fixed it The owner had to remove the upper intake manifold to access the rear bank. While doing so, they discovered the injector wiring harness was rubbing against a bracket near the firewall, causing a short. Repairing the wire and protecting it with conduit resolved the issue.

OEM Part Supersession History

• 12638530 → 12669384 — Updated design or manufacturer change for improved reliability or performance.
  Heads up: The newer part number 12669384 is the correct service replacement for the original. Aftermarket equivalents include ACDelco 217-3445 and Bosch 0261500400.

Model Year Variations Within This Range

• 2010-2011 vs 2012-2015: The primary V6 engine changed from the 3.0L (LF1/LFW) in 2010-2011 to the 3.6L (LFX) in 2012-2015. While both are direct-injection V6 engines and suffer from the same wiring harness chafing issue described in the TSBs, some specific component locations, ground points, and intake manifold removal procedures may vary slightly. However, the diagnostic approach for P0273 remains identical.