P0271 on 2011-2014 Chevrolet Camaro: Cylinder 4 Injector Circuit High Causes and Fixes

What's Unique About the 2011-2014 Chevrolet CAMARO

For this generation of Camaro, along with a wide range of other GM vehicles from the same era using the same engines, there is a well-documented issue with the fuel injector wiring harness. A General Motors Technical Service Bulletin (TSB #PIP4924D) specifically advises technicians to look for the harness rubbing through against engine components like the intake plenum, valve cover bolts, or fuel lines. Forum discussions on Camaro5.com frequently cite this exact issue, with owners finding melted or chafed wires on the passenger side harness where it runs close to headers or the engine block. This makes a wiring fault a much higher probability on this car than on a vehicle without this known issue.

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 unstable idle
• Engine hesitates or stumbles during acceleration
• Noticeable loss of engine power
• Increased fuel consumption
• A smell of raw fuel from the exhaust may be present in some cases
• Service Stabilitrak message may appear on the dash along with the check engine light.

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 is known to rub against the intake plenum, valve cover bolts, fuel lines, or the side of the cylinder head, causing shorts or open circuits. Owners on forums like Camaro5 have found the harness that runs along the passenger side of the engine is particularly susceptible to melting or rubbing on exhaust headers or the engine block.
   How to confirm: Visually inspect the entire fuel injector harness, paying close attention to the contact points mentioned in the TSB and forum posts. Gently move the harness while the engine is running (use caution) to see if the misfire changes. Test for a short to voltage on the control wire at the injector connector using a multimeter.
   Typical fix: Repair the damaged wire(s) by soldering and using heat-shrink tubing. Protect the harness by re-routing it or wrapping it with high-temperature wire loom or Tesa tape to prevent future rubbing. In severe cases, a replacement harness pigtail may be needed.
   Est. part cost: $5-$50
2. Faulty Cylinder 4 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector Injectors can fail over time due to internal coil windings breaking, leading to an open circuit which can trigger a 'Circuit High' code. While less common than the wiring issue on this platform, it's a frequent failure point for any vehicle.
   How to confirm: Swap the cylinder 4 fuel injector with an injector from another cylinder (e.g., cylinder 2). Clear the codes and drive the vehicle. If the code changes to P0265 (Cylinder 2 Injector Circuit High), the injector is faulty. You can also test the injector's internal resistance with a multimeter; a reading of 'OL' (Open Line) indicates a failed coil. Compare the reading to a known good injector; it should be between 11 and 15 ohms.
   Typical fix: Replace the faulty fuel injector. It is often recommended to replace all injectors on that bank, or all injectors if they are high mileage.
   Est. part cost: $50-$170
3. Poor Connection or Damaged Connector ⚪ Low Probability
   How to confirm: Disconnect the cylinder 4 injector connector and inspect for corrosion, bent, backed-out, or melted pins. Ensure the connector clicks securely into place and that the locking tab isn't broken.
   Typical fix: Clean the connector terminals with electrical contact cleaner or replace the connector pigtail if it's damaged.
   Est. part cost: $15-$40

Rare But Worth Checking

• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is the least likely cause. The ECM's internal driver for the cylinder 4 injector can fail, but all other possibilities, especially wiring, must be exhaustively ruled out first. This should be considered only after confirming the wiring and injector are good.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0271 is present.
2. Crucial Step: Perform a detailed visual inspection of the fuel injector wiring harness as outlined in TSB #PIP4924D. Pay special attention to the passenger side harness where it runs near the exhaust manifold/header, valve cover, and intake plenum for any signs of rubbing, melting, or chafing.
3. If harness damage is found, repair the wiring and protect the harness. Clear the codes and test drive. If the code returns, proceed to the next step.
4. If no harness damage is visible, disconnect the cylinder 4 injector connector. Check for corrosion or damage to the pins and terminals.
5. Use a 'noid light' to test the signal at the injector connector. The light should flash steadily while cranking the engine, indicating the ECM is attempting to fire the injector. If the noid light does not flash, it points to a wiring or ECM issue.
6. Test the injector's resistance. Disconnect the injector and use a multimeter set to Ohms to measure the resistance between its two terminals. A good injector will typically read between 11-15 Ohms. An 'OL' or infinite reading means the injector's internal coil is open and the injector is bad.
7. If the resistance is good, swap the cylinder 4 injector with one from another cylinder (like cylinder 2). Clear codes and run the engine. If the fault moves to the new cylinder (e.g., P0265), the injector is bad.
8. If the fault stays on cylinder 4 after the swap, the problem is definitively in the wiring between the ECM and the injector connector.
9. Perform a continuity test on both the power and control wires from the injector connector back to the ECM connector to find any open circuits or shorts.
10. If the injector and wiring are confirmed to be good, the final possibility is a faulty ECM driver.

Parts You'll Likely Need

• Fuel Injector Wiring Harness Repair Supplies — To fix the most common cause: a chafed wire. This includes Tesa tape, wire loom, and potentially butt connectors.
  OEM price range: $5-$20
  Aftermarket price range: $5-$20
• Fuel Injector (OEM #ACDelco 12638530 (also listed as 217-3445) for 3.6L V6 LLT/LFX engines. For V8 engines (LS3/L99), part numbers vary, check with VIN.) — This is the second most likely cause if the wiring harness is intact.
  Trusted brands: ACDelco, Bosch, Standard Motor Products
  OEM price range: $90-$170
  Aftermarket price range: $50-$110
• Fuel Injector Connector Pigtail (OEM #GM 19368140 is a common pigtail, but verify fitment.) — Needed if the connector itself is damaged, corroded, or melted.
  Trusted brands: ACDelco, Dorman, Standard Motor Products
  OEM price range: $25-$50
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• P0304 — This code means 'Cylinder 4 Misfire Detected'. Since P0271 indicates a problem with the fuel supply to cylinder 4, a misfire in that same cylinder is a direct consequence.
• P0204 — This code for 'Injector Circuit/Open - Cylinder 4' is very closely related and can sometimes appear with P0271, as both point to an electrical fault in the same circuit.
• P0300 — This code for 'Random/Multiple Cylinder Misfire' can occur if the wiring harness issue is intermittent or if the resulting engine imbalance affects other cylinders.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Recommends careful inspection of the fuel injector wiring harness for rubbing or open wires at common contact points like the intake plenum, valve cover bolts, against the fuel line, and on the side of the head under the plenum for a variety of injector circuit codes, including P0271.

Platform-Specific Known Issues

• A known issue documented in GM Technical Service Bulletin #PIP4924D involves the fuel injector wiring harness rubbing through on various engine components, leading to codes like P0271.
• Owners on the Camaro5 forums have specifically reported the harness on the passenger side (where cylinder 4 is located on a V8) melting from contact with aftermarket or even stock exhaust headers.