P0205 on 2012-2014 Chevrolet Impala: Cylinder 5 Injector Circuit Causes and Fixes

What's Unique About the 2012-2014 Chevrolet IMPALA

The 2012-2014 Impala, primarily equipped with the 3.6L LFX V6 engine, has a documented history of injector circuit issues. General Motors issued Technical Service Bulletin #PIP4924D for various models including the 2012 Impala, which addresses a range of injector circuit codes, including P0205. This TSB specifically warns technicians to inspect for the fuel injector wiring harness rubbing through (chafing) against engine components. Common chafe points are against the intake plenum, at valve cover bolts, against a fuel line, or on the side of the cylinder head under the plenum. This known vulnerability makes a wiring inspection a critical first step.

Diagnostic Flowchart

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

Generation note: This range covers two generations. The 2012 and 2013 models belong to the ninth generation. The 2014 model year was a split, featuring both the ninth-generation "Impala Limited" (often for fleets) and the redesigned tenth-generation Impala. Both generations offered the 3.6L LFX V6 engine, to which this guide primarily applies.

Symptoms You May Notice

• Engine running rough or shaking, especially at idle
• Noticeable engine misfire
• Flashing or steady Check Engine Light
• Reduced engine power and poor acceleration
• Decreased fuel economy
• Engine may be hard to start or stall

Most Likely Causes

1. Failed Fuel Injector (Cylinder 5) 🔴 High Probability → Shop Fuel Injector Direct injection (DI) fuel injectors operate under high pressure and can fail electrically over time.
   How to confirm: Disconnect the injector and measure the resistance across its two terminals with a multimeter. For the 3.6L LFX engine, the expected value is approximately 1.9-2.3 Ohms at room temperature. A reading of infinity (open) or near zero (short) indicates a bad injector. An alternative is to swap the cylinder 5 injector with an adjacent one (like cylinder 3) and see if the trouble code follows to the new cylinder (e.g., P0203). This requires removing the intake manifold.
   Typical fix: Replace the faulty fuel injector. Since accessing the rear bank injectors requires significant labor, many technicians recommend replacing all three (cylinders 1, 3, 5) 🎬 Watch this walkthrough for replacing 3.6L fuel injectors and gaskets. at the same time.
   Est. part cost: $50-$120
2. Wiring Harness or Connector Fault 🔴 High Probability GM TSB #PIP4924D specifically mentions injector circuit codes on this platform, suggesting a known vulnerability in the wiring harness. The harness is known to rub against the intake plenum, valve cover bolts, fuel lines, or the cylinder head itself, causing wires to chafe and break.
   How to confirm: Visually inspect the wiring leading to the cylinder 5 injector for any signs of chafing, melting, or corrosion, paying close attention to the known rub spots. Check the connector for loose pins or damage. Use a noid light in the injector connector; it should flash while cranking the engine, confirming a signal from the ECM. 🎬 See how to diagnose injector circuit codes on GM engines. A failed noid light test points directly to a wiring or ECM issue.
   Typical fix: Repair the damaged section of the wire harness or replace the injector connector pigtail.
   Est. part cost: $15-$45
3. Faulty Powertrain Control Module (PCM) ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This should be the last step after confirming the injector and wiring are both in good condition. A professional diagnosis is often needed to confirm a failed injector driver circuit within the PCM. This is a rare failure.
   Typical fix: Replace and reprogram the Powertrain Control Module.
   Est. part cost: $300-$800

Diagnosis Steps

1. Connect an OBD-II scanner to verify the P0205 code and check for any other related codes, such as P0305.
2. Locate cylinder 5 on the 3.6L V6 engine. On this transverse engine, the cylinders closer to the firewall are the odd-numbered ones (1, 3, 5), and cylinder 5 is on the passenger side. Access to this injector and its wiring requires removing the upper intake manifold.
🎬 Watch: Step-by-step guide to removing the intake and replacing injectors.
3. With the intake manifold removed, carefully inspect the wiring harness and electrical connector for the cylinder 5 fuel injector. Pay close attention to the known chafe points mentioned in TSB PIP4924D: against the intake plenum, valve cover bolts, fuel lines, and the side of the cylinder head.
4. Disconnect the injector and use a multimeter to test the resistance between the two pins on the injector itself. For the LFX engine, the reading should be around 1.9-2.3 ohms. An infinite reading (open) or zero reading (short) means the injector has failed.
5. If the injector resistance is good, plug a 'noid light' into the harness connector. Crank the engine. A flashing light indicates the ECM is sending the correct signal, and the problem is likely the injector. No light or a steady light points to a problem with the wiring or the ECM.
6. If the noid light does not flash, check for 12-volt power at one pin of the connector with the key on. Then, check the continuity of the ground/control wire from the connector back to the ECM to find a potential break in the wire.
7. If both the injector and wiring test good, the final possibility is a failed injector driver circuit within the ECM, which may require professional diagnosis. This is the least likely cause.

Parts You'll Likely Need

• Fuel Injector (OEM #12638530, 12669384, 12632255, 12611545) — This is a common component to fail internally, causing an open or short in the circuit. The LFX engine uses direct injectors.
  Trusted brands: ACDelco, Bosch, Standard Motor Products
  OEM price range: $70-$120
  Aftermarket price range: $50-$90
• Fuel Injector Connector Pigtail (OEM #ACDelco PT2183 (GM #88988963)) — The connector itself or the wires directly attached to it can become brittle, corroded, or damaged from harness chafing, requiring replacement.
  Trusted brands: ACDelco, Dorman, NAPA Echlin
  OEM price range: $30-$45
  Aftermarket price range: $15-$30
• Upper Intake Manifold Gaskets — These are single-use gaskets that must be replaced anytime the intake manifold is removed to access the rear bank of injectors.
  Trusted brands: Fel-Pro, ACDelco, Mahle
  OEM price range: $25-$40
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• P0305 — This code means "Cylinder 5 Misfire Detected." Since P0205 indicates the fuel injector isn't firing correctly, a misfire in that cylinder is a direct and expected consequence.
• P0201, P0202, P0203, P0204, P0206 — The presence of multiple injector circuit codes alongside P0205, as listed in TSB #PIP4924D, strongly suggests a systemic problem like a damaged wiring harness affecting several cylinders, rather than multiple individual injector failures.
• P2146, P2149 — These codes indicate a fault in an entire injector group ('A' for cylinders 1,3,5 or 'B' for 2,4,6). Their presence alongside P0205 points even more strongly to a shared wiring problem, as documented in TSB PIP4924D.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Addresses Service Engine Soon lamp with misfires and various injector circuit DTCs, including P0205. Recommends inspecting the wiring harness for chafing as a primary diagnostic step.

Platform-Specific Known Issues

• TSB #PIP4924D: Known Wiring Harness Chafing: This Technical Service Bulletin from GM addresses diagnoses for engine misfires accompanied by various injector circuit DTCs, including P0205, on the 2012 Impala and its platform mates. It specifically directs technicians to investigate the wiring harness for rub-through damage against the intake plenum, valve cover bolts, and fuel lines before replacing any components.
• Common Owner Misdiagnosis: A frequent pattern seen in owner forums involves the unnecessary replacement of the cylinder 5 spark plug and ignition coil in an attempt to fix the accompanying P0305 misfire code. This rarely solves the P0205 electrical fault, which is almost always caused by the injector or its wiring. The correct procedure is to diagnose the circuit fault first.

Mechanic-Grade Diagnostic Values

• Fuel Injector Internal Resistance (3.6L LFX GDI) — expected: 1.5 - 2.5 Ohms. Failure: A reading of OL/infinity indicates an open circuit; a reading near 0 Ohms indicates a shorted injector.
• Injector Circuit Continuity (from ECM to Injector Connector) — expected: < 0.5 Ohms. Failure: High resistance or an open circuit (OL) reading indicates a break or corrosion in the wire.
• Injector Power Supply (at injector connector) — expected: Battery Voltage (approx. 12V) with Key On, Engine Off.. Failure: Low or no voltage points to a problem in the power supply wire or its associated fuse.
• Mass Airflow (MAF) Sensor at idle (Live Data) — expected: ~3.6 g/s (grams/second). Failure: While not a direct cause for P0205, an erratic or wildly incorrect MAF reading can indicate broader engine management or wiring issues that could be related.

Hidden / Shadow Codes Worth Checking

• P124B: This manufacturer-specific code can indicate a short in the fuel injector's high voltage circuit. (see via May be visible on some professional-grade OBD-II scanners, appears on some 2012 Impala models.)

Scan Tool Commands That Help

• GDS2 (or other professional scan tool): Injector Balance Test — This bidirectional test allows the technician to command each injector to fire for a set duration and measures the corresponding drop in fuel pressure. A cylinder that shows less of a pressure drop than the others indicates a poorly flowing or non-functioning injector. GM TSB PIP4964F specifically directs technicians to use this test when diagnosing fuel system codes.

Wiring & Ground Locations

• G111 — On the engine block, located above the starter motor.. This is a primary engine ground. A poor or corroded connection here can cause erratic behavior and voltage drops in multiple engine sensor and actuator circuits, including the fuel injectors.
• G112 — On the chassis, located near the battery.. Serves as another critical grounding point for the engine harness. A loose or corroded G112 can introduce electrical noise and unstable voltages, potentially triggering circuit fault codes.
• Engine Harness Chafe Point (TSB PI0631G) — The engine wiring harness may rub through on the front right or rear right side of the transmission housing.. This is an additional documented chafe point beyond those on the engine itself. A short in the harness at this location can affect various circuits, including the one for the cylinder 5 injector.

Real Owner Repair Stories

• YouTube channel 'BULLDOG' (2014 Chevrolet Impala 3.6L) — Check engine light came on, code read for injector circuit (specifically P0203, but diagnosis is identical for P0205). The code returned after clearing and the engine began misfiring.
  ❌ Tried (didn't work) Clearing the code was only a temporary fix.
  ✅ What actually fixed it The mechanic tested the resistance of the injectors on the affected bank. Two injectors read 2.2 ohms, while the faulty one read open (infinite resistance). Replacing the single failed fuel injector resolved the code and misfire.
• YouTube Channel 'Car Confections' (GM 3.6L LFX Engine (in a 9th Gen Impala)) — Not specified, but injector replacement was performed.
  ❌ Tried (didn't work) The user initially purchased and installed aftermarket injectors which were described as 'junk' and did not perform correctly.
  ✅ What actually fixed it The problem was resolved by purchasing and installing OEM-quality fuel injectors from a reputable source. This serves as a strong recommendation to avoid low-quality aftermarket parts for this specific repair.

Model Year Variations Within This Range

• 2012-2014: While the core 3.6L LFX engine is shared with other GM vehicles like the Camaro, the Impala version has a different ECM tune for lower horsepower (approx. 300 hp vs 323 hp). It also uses different intake and exhaust manifolds to accommodate the transverse FWD layout. This does not significantly alter the P0205 diagnosis but highlights that parts like the ECM are not interchangeable with other LFX-equipped models.