P0276 on 2010-2014 Cadillac SRX: Cylinder 6 Injector Circuit Low Causes and Fixes

What's Unique About the 2010-2014 Cadillac SRX

For this generation of Cadillac SRX with either the 3.0L or 3.6L V6 engine, the primary suspect for a P0276 code is not the injector itself, but the wiring harness leading to it. General Motors issued a Technical Service Bulletin (PIP4924D) that specifically calls out a known issue where the fuel injector wiring harness can rub against engine components, causing shorts or open circuits. This makes a thorough harness inspection the critical first step in diagnosis, as simply replacing the injector will not solve a wiring problem.

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 vibrating idle
• Reduced engine power and poor acceleration
• Engine misfire, which may feel like shaking or stumbling
• Decreased fuel economy
• Engine stalling
• Hard starting condition

Most Likely Causes

1. Chafed or Damaged Fuel Injector Wiring Harness 🔴 High Probability → Shop Engine Wiring Harness As documented in GM TSB PIP4924D, the harness routing on these V6 engines makes it susceptible to rubbing against the intake plenum, valve cover bolts, fuel lines, or the cylinder head itself. Engine vibration over time causes the plastic loom to wear through, exposing the injector control wires to a short-to-ground condition on the engine block or brackets.
   How to confirm: Visually inspect the entire length of the fuel injector harness, paying close attention to the areas mentioned in the TSB. Specifically check where the harness bends around the rear of the cylinder head for cylinder 6. Look for worn-through plastic conduit, exposed copper wires, or shiny rub marks on engine components. It may be necessary to remove the engine cover and gently move the harness to see the contact points.
   Typical fix: Repair the damaged section of wire with a new connector pigtail or by soldering in a new section of wire and sealing with heat-shrink tubing. Secure the harness away from the contact point using zip ties or re-routing to prevent future damage. In severe cases where multiple wires are damaged, the entire engine harness may need replacement.
   Est. part cost: $15-$50 for a pigtail connector
2. Faulty Cylinder 6 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector The 3.0L LF1 and 3.6L LFX are direct injection engines, and their injectors operate under very high pressure. Over time, internal components can fail, leading to electrical faults like an open or shorted coil. While less common than the wiring issue on this platform, injector failure is still a significant possibility.
   How to confirm: After confirming the wiring is intact, swap the cylinder 6 injector with an injector from another cylinder (e.g., cylinder 4). Clear the codes and drive the vehicle. If the code returns for the new cylinder (P0270 for cylinder 4), the injector is faulty. You can also test the injector's resistance with a multimeter; a typical resistance for the 3.6L LFX is 1.2-1.8 Ohms, while the 3.0L LF1 is ~11-14 Ohms. An out-of-spec reading indicates failure.
   Typical fix: Replace the faulty fuel injector. For direct injection engines, it is critical to also replace the Teflon seal on the injector tip. It is often recommended to replace all injectors on the same bank or all six for high-mileage vehicles to ensure balanced fuel delivery.
   Est. part cost: $70-$150 for a single injector
3. Loose or Corroded Injector Connector ⚪ Low Probability
   How to confirm: Unplug the connector at the cylinder 6 fuel injector and inspect the pins and terminals for any signs of corrosion (green or white powder) or damage. The locking tab can become brittle and break, leading to a loose connection. Ensure it clicks securely back into place.
   Typical fix: Clean the connector terminals with electrical contact cleaner. If the connector or its locking tab is broken, replace it with a new pigtail connector, such as ACDelco PT2183.
   Est. part cost: $15-$50

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare. The internal driver circuit for the injector can fail, but all other possibilities, especially wiring and the injector itself, should be exhaustively ruled out before considering PCM replacement. A PCM failure would typically be confirmed by verifying a good signal wire from the PCM to the injector but no pulse command from the module itself.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner. 🎬 Watch: Understanding the P0276 injector circuit low trouble code. Note P0276 and any other codes present, such as P0306.
2. Perform a detailed visual inspection of the fuel injector wiring harness as per TSB PIP4924D. Focus on the area where the harness routes around the back of the driver's side cylinder head (for cylinder 6). Check for chafing against the intake, valve covers, fuel lines, and cylinder head.
3. If damage is found, repair the wiring using a pigtail connector or by soldering and heat-shrinking the damaged section. Secure the harness away from the sharp edge. Clear codes and test drive.
4. If the wiring appears perfect, test the circuit. Use a 'noid light' on the cylinder 6 injector connector to verify the PCM is sending a pulse signal. The light should flash with the engine running.
5. If a pulse is present, the issue is likely the injector itself. Turn the engine off. Test the injector's internal resistance with a multimeter. Compare the reading to the manufacturer's specification (1.2-1.8 ohms for 3.6L LFX, ~11-14 ohms for 3.0L LF1).
6. As a final confirmation, swap the cylinder 6 injector with one from another cylinder (e.g., cylinder 4). This requires removing the upper intake manifold. 🎬 Watch this walkthrough for removing the intake and replacing injectors. If the trouble code follows the injector to its new location (e.g., P0270 for cylinder 4), the injector is confirmed faulty.
7. If there is no pulse signal at the connector (step 4) and the wiring from the connector to the PCM is confirmed to be good (continuity test), the problem may be in the PCM's injector driver circuit, which is a rare failure.

Parts You'll Likely Need

• Fuel Injector Wiring Harness Pigtail (OEM #ACDelco PT2183 (GM 88988963)) — This is needed to repair a damaged connector or a chafed wire near the connector, which is the most common cause according to GM's TSB.
  Trusted brands: ACDelco, Dorman
  OEM price range: $30-$60
  Aftermarket price range: $15-$40
• Fuel Injector (OEM #ACDelco 217-3433 (GM 12638530, 12669384)) — If the wiring is intact, the injector itself is the next most likely component to have failed. The LFX engine uses direct injectors.
  Trusted brands: ACDelco, Bosch, Standard Motor Products
  OEM price range: $120-$180
  Aftermarket price range: $70-$150

Related Codes That Often Appear With This One

• P0306 — P0306 indicates a misfire on cylinder 6. Since P0276 means the cylinder 6 injector isn't working correctly, it will lead to a misfire on that same cylinder.
🎬 See this guide on diagnosing and fixing cylinder 6 misfires.
• P0201-P0205, P0261, P0262, etc. — The TSB PIP4924D lists a large number of injector circuit codes. If the harness is chafed in a location where multiple injector wires are bundled, you may see codes for other cylinders as well, indicating a more widespread wiring issue.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: SES Light And Misfire With Injector Codes

Platform-Specific Known Issues

• GM Technical Service Bulletin PIP4924D specifically addresses a range of fuel injector codes, including P0276, on 2010-2014 SRX models. The bulletin points to the fuel injector wiring harness rubbing through against various engine components, causing electrical faults.
• A YouTube video by a 9th Gen Impala owner with the same 3.6L LFX engine documents getting a P0276 code specifically in certain weather conditions, which ultimately led them to perform an injector and harness repair. This highlights how intermittent shorts can be.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (3.6L LFX V6) — expected: 1.2 - 1.8 Ohms. Failure: A reading outside this range, OL (open), or near zero indicates an internal injector fault.
• Fuel Injector Resistance (3.0L LF1 V6) — expected: ~11 - 14 Ohms. Failure: A significant deviation from this range, OL (open), or a short (near 0 Ohms) indicates a fault in the high-impedance injector's coil.
• High-Pressure Fuel Rail Pressure (at idle) — expected: 1.9-5.0 MPa (276-725 PSI). Failure: Pressure significantly below the PCM's desired pressure reading on a scan tool can indicate other fuel system issues, though not typically a direct cause of a single injector circuit code.
• Injector Circuit Voltage (Key On, Engine Off) — expected: Battery Voltage (approx. 12.6V) on the power supply wire (Pink/Black) and near Battery Voltage on the control wire (e.g., Dk Blue/Lt Blue for Cyl 6) with the injector disconnected.. Failure: 0V on the control wire with the injector disconnected indicates a short to ground in the harness between the PCM and the injector.

Scan Tool Commands That Help

• GDS2 (GM Tech 2): Fuel Injector Balance Test — This bidirectional test allows a technician to command each injector to fire and measures the corresponding drop in fuel rail pressure. If all other injectors show a similar pressure drop but cylinder 6 shows a much smaller or no drop, it confirms the injector is not flowing fuel, even if it passes a resistance test. This can help isolate a clogged or mechanically stuck injector.
• GDS2 (GM Tech 2): Cylinder Power Balance — This function graphically displays the contribution of each cylinder to engine speed. It can be used to quickly confirm that cylinder 6 is not contributing power, which is the expected result of a P0276 fault. It's a good initial step to verify the symptom before diving into electrical tests.

Wiring & Ground Locations

• G103 / G107 — On the front of the passenger side (G103) or driver side (G107) cylinder head.. These are the primary engine block to chassis grounds. While a poor ground here typically causes multiple, widespread issues, a loose or corroded connection can introduce electrical noise and voltage drops that could potentially affect sensitive circuits like injector drivers. It's a 'good practice' check when dealing with any engine electrical fault.
• ECM Connector X1 — One of the main multi-pin connectors at the Engine Control Module (ECM).. The control wire for the cylinder 6 fuel injector originates at a specific pin in this connector. When diagnosing a 'no pulse' condition where the wiring harness appears intact, testing for a signal directly at the ECM pin can definitively rule the PCM in or out as the cause.

Real Owner Repair Stories

• cadillacforums.com user (2012 Cadillac SRX 3.6L LFX) — Check engine light with codes P0276 and P0306 (Cylinder 6 misfire).
  ❌ Tried (didn't work) Replacing the spark plug for cylinder 6., Replacing the fuel injector for cylinder 6.
  ✅ What actually fixed it After replacing the injector did not fix the problem, the owner inspected the wiring harness more closely. They found a chafed wire in the harness near the rear of the cylinder head, exactly as described in TSB PIP4924D. Repairing the broken wire and protecting the harness resolved the codes.

OEM Part Supersession History

• GM 12638530 → GM 12669384 — Part update/revision by the manufacturer.
  Heads up: This part number series is for the 3.6L LFX engine. It is not compatible with the 3.0L LF1 engine.
• GM 12629927 → ACDelco 217-3449 (also GM 12642021) — Part update and consolidation.
  Heads up: These part numbers are for the 3.0L LF1 engine (2010-2011) ONLY and are not compatible with the 3.6L LFX engine.

Model Year Variations Within This Range

• 2010-2011: These models use the 3.0L LF1 V6 engine. The fuel injectors are a high-impedance design with a resistance of approximately 11-14 Ohms. The correct OEM part number is GM 12629927 or its successor, ACDelco 217-3449.
• 2012-2014: These models use the 3.6L LFX V6 engine. The fuel injectors are a low-impedance design with a resistance of approximately 1.2-1.8 Ohms. The correct OEM part number is GM 12634126 or its successor, 12669384. These parts are not interchangeable with the 3.0L engine.