P0273 on 2011-2014 Chevrolet Camaro: Cylinder 5 Injector Circuit Low Causes and Fixes

What's Unique About the 2011-2014 Chevrolet CAMARO

For this generation of Camaro, and a wide range of other GM vehicles with the 3.6L V6 and V8 engines, a well-documented issue is the fuel injector wiring harness rubbing through its insulation where it contacts the engine. This is detailed in GM Technical Service Bulletin #PIP4924D. The TSB specifically calls out chafe points against the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head. This makes a wiring issue a much higher-than-usual probability compared to other vehicles where the injector itself is the more common failure point.

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 (may be flashing if misfire is severe)
• Rough or shaky idle
• Engine misfire, which may be felt as a shudder or heard as a popping sound
• Hesitation or lack of power during acceleration
• Reduced fuel economy
• "Service Stabilitrak" message on the driver information center
• "Engine Power is Reduced" message
• Strong fuel smell from the exhaust if the injector is stuck open

Most Likely Causes

1. Chafed/Damaged Fuel Injector Wiring Harness 🔴 High Probability → Shop Engine Wiring Harness A GM Technical Service Bulletin (PIP4924D) specifically calls out inspecting the fuel injector wiring harness for rubbing through on this platform. The harness routing can cause it to make contact with engine components like the intake plenum, valve cover bolts, fuel lines, or the side of the cylinder head, leading to a short to ground. Forum users on Camaro5.com have documented this issue, sometimes finding melted wires near the headers, especially after engine work.
   How to confirm: Visually inspect the entire length of the wiring harness leading to the cylinder 5 fuel injector. Pay close attention to any areas where it is routed near or touches the cylinder head, valve covers, or intake manifold. Look for worn insulation, exposed copper wires, or melted plastic loom. Wiggle the harness with the engine running to see if the misfire changes, which can indicate an intermittent short. 🎬 Watch: Finding and fixing a hidden broken injector wire.
   Typical fix: Repair the damaged section of the wire. This involves cutting out the damaged portion, splicing in a new piece of wire using weatherproof butt connectors, and wrapping the repair in protective loom or high-temperature tape. 🎬 See how to properly solder and shrink-wrap wiring repairs. Reroute the harness using zip ties to prevent future rubbing. In some cases, owners have opted to replace the entire engine wiring harness.
   Est. part cost: $5-$25 for wire repair supplies, $230+ for a new harness
2. Faulty Cylinder 5 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: Swap the cylinder 5 fuel injector with an injector from another cylinder (e.g., cylinder 3). Clear the codes and drive the vehicle. If the code changes to P0267 (Cylinder 3 Injector Circuit Low), the injector is faulty. If P0273 returns, the problem is in the wiring or PCM. You can also test the injector's internal resistance with a multimeter (it should be within a specific range, typically 12-15 ohms). A user on Camaro5.com noted a cheap scanner correctly identified the failed injector, which was confirmed bad after testing.
   Typical fix: Replace the faulty fuel injector. 🎬 Watch this walkthrough for replacing injectors on a V8 Camaro. It is often recommended to replace all injectors as a set if they are high mileage to ensure consistent performance.
   Est. part cost: $40-$120
3. Damaged or Corroded Injector Connector ⚪ Low Probability
   How to confirm: Unplug the connector at the cylinder 5 fuel injector and inspect the terminals for corrosion, moisture, bent or pushed-out pins. Ensure it clicks securely into place. Wiggling the connector while the engine is running can help identify a poor connection.
   Typical fix: Clean the connector terminals with electrical contact cleaner. If the connector housing or terminals are damaged, replace the connector pigtail.
   Est. part cost: $15-$40
4. Faulty Powertrain Control Module (PCM) ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This is diagnosed by exclusion. If the injector, wiring, and connector are all confirmed to be good through extensive testing (continuity checks, short-to-ground tests), the PCM's internal driver for that injector may have failed. This requires professional-level diagnostics.
   Typical fix: Replace and reprogram the Powertrain Control Module.
   Est. part cost: $300-$800

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner and confirm P0273 is present. Note any other codes like P0305 and look for the "Service Stabilitrak" message.
2. Locate cylinder 5. On the 3.6L V6, it is the rear-most cylinder on the passenger's side (right bank). On the 6.2L V8, it is the third cylinder back on the driver's side (left bank).
3. Crucial Step: Carefully inspect the wiring harness going to the cylinder 5 fuel injector. As per TSB PIP4924D, follow it back as far as possible, looking for any signs of rubbing, melting, or chafing against the engine block, cylinder head, valve cover bolts, or intake plenum. This is the most common fix.
4. If the wiring looks good, disconnect the connector at the injector. Check for corrosion or damage to the pins and terminals.
5. Use a 'noid light' to test for a signal from the PCM. Plug it into the injector connector. The light should flash when the engine is cranked or running, indicating the PCM is commanding the injector to fire.
6. If the noid light flashes, the wiring to the injector is likely okay. Test the injector itself. You can measure its resistance with a multimeter (typically 12-15 ohms) or swap it with another cylinder's injector (e.g., cylinder 3) and see if the fault code moves to P0267.
7. If the noid light does not flash, the problem is in the wiring between the PCM and the injector, or a faulty PCM driver. Use a multimeter to check for continuity on the control and power wires back to the PCM. Also, check for a short to ground on the control wire.
8. If the wiring is confirmed to be good and there is no signal, the PCM is the likely point of failure. This is rare.

Parts You'll Likely Need

• Fuel Injector (OEM #12638530 (V6 LLT), 12576341 (V8 LS3)) — If the injector itself has an internal short or has failed, it will need to be replaced. This is a common failure point after the wiring has been ruled out. Part number 12638530 is for the 3.6L V6.
  Trusted brands: ACDelco, Bosch
  OEM price range: $70-$120
  Aftermarket price range: $40-$80
• Fuel Injector Connector Pigtail (OEM #13580230) — If the plastic connector or its terminals are damaged or corroded, replacing the pigtail is the proper repair. GM part number 13580230 is a common pigtail for this application.
  Trusted brands: ACDelco, Dorman
  OEM price range: $25-$40
  Aftermarket price range: $15-$25

Related Codes That Often Appear With This One

• P0305 — P0305 means 'Cylinder 5 Misfire Detected'. The low voltage condition of P0273 prevents the injector from delivering fuel, which directly causes a misfire in that cylinder.
• P0205 — This is a more general 'Cylinder 5 Injector Circuit Malfunction' code and is often set alongside the more specific P0273.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Intermittent Misfire, Fuel Injector, And Or Injector Driver DTCs. This bulletin advises technicians to inspect the fuel injector wiring harness for rubbing through on the engine, which can cause a variety of injector circuit codes, including P0273. Specific chafe points mentioned are against the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head.

Platform-Specific Known Issues

• A known issue documented in Technical Service Bulletin #PIP4924D involves the fuel injector wiring harness rubbing through its insulation where it makes contact with the engine, causing a short circuit and triggering codes like P0273.
• A user on Camaro5.com reported finding the main engine harness melted on a header tube, causing multiple electrical issues. After repairing the wires and securing the harness, the issue was resolved.
• Another Camaro5.com user with similar injector circuit codes ultimately traced the problem to a short in the engine wiring harness and fixed it by replacing the entire engine wiring harness.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance (V8 LS3/L99 - Port Injection) — expected: 11.8 - 12.6 Ohms. Failure: A reading significantly outside this range, or a large variance between injectors, indicates a faulty injector coil.
• Fuel Injector Coil Resistance (V6 LLT/LFX - Direct Injection) — expected: 1.5 - 1.7 Ohms (cold). Failure: A reading of 0 ohms (short) or infinite/OL (open) indicates a failed injector. Resistance will change as the injector heats up.
• Injector Circuit Voltage (Key On, Engine Off) — expected: 11.5V - 12.5V (Battery Voltage). Failure: Voltage below 10V at the injector connector (power feed wire to ground) points to a problem in the power supply circuit, not the injector itself.

Scan Tool Commands That Help

• GDS2 / Tech 2: Injector Balance Test (or Active Fuel Injector Tester - AFIT) — This bidirectional test is used to diagnose a suspected faulty injector without removing it. The tool commands the ECM to pulse each injector individually and measures the corresponding drop in fuel rail pressure. If the pressure drop for cylinder 5 is significantly different from the others (GM specifies a variance of less than 20 kPa or 3 psi from the average), it indicates a flow problem with that injector.

Wiring & Ground Locations

• Cylinder 5 Injector Control Pin (V8 LS3/L99) — On the 2010-2011 models, the control wire for the cylinder 5 injector is a Tan/White wire located at Pin 18 of the X2 (80-way gray) ECM connector.. This pin is the specific location to test for continuity and shorts to ground on the control circuit between the ECM and the injector connector.
• Cylinder 5 Injector Control Pin (V6 LFX) — On a 2013 V6 LFX, the wiring diagram shows the fuel injector 5 control wire is located at the ECM, but the specific pin number requires consulting the exact service manual diagram for that year.. Knowing the ECM pin allows for an end-to-end test of the injector control wire to rule out a wiring fault between the module and the component.
• G102 / G103 Engine Grounds — On many GM platforms, major engine grounds are located at the rear of the cylinder heads (G102) or on the cowl above the brake booster (G103). Forum users on Camaro5.com confirm grounds at the back of each cylinder head and near the water pump.. The ECM and its driver circuits rely on a solid ground reference. A loose or corroded engine ground can cause a voltage drop across the entire system, leading to erratic sensor readings and potentially triggering low voltage circuit codes like P0273.

OEM Part Supersession History

• 12638530 → 12669384 — Standard part update/revision by the manufacturer.
  Heads up: This part number is specific to the 3.6L LLT V6 engine (2010-2011). It is not compatible with the LFX V6 (2012-2014) due to engine design changes.

Model Year Variations Within This Range

• 2011 vs 2012-2014 (V6 Models): The 2011 Camaro uses the 3.6L LLT V6 engine, which has a Bosch ECM and external exhaust manifolds. Starting in 2012, the V6 was updated to the LFX engine, which features cylinder heads with integrated exhaust manifolds, a composite intake manifold, and uses a Delphi ECM. Due to these changes, the engine wiring harness, fuel injectors, and ECM are not interchangeable between LLT and LFX models.