P0201 on 2012-2014 Chevrolet Impala: Injector Circuit Malfunction Causes & Fixes

What's Unique About the 2012-2014 Chevrolet IMPALA

For the 2012-2014 Impala with the 3.6L LFX V6 engine, a P0201 code is a strong indicator of a fuel delivery problem at cylinder 1. However, this platform is subject to GM-specific Technical Service Bulletins, including #PIP4924D and #PI1067B, which highlight a known vulnerability: the engine wiring harness is prone to chafing. Common rub points are against the intake plenum, valve cover bolts, fuel lines, the side of the cylinder head, and the metal ECM bracket. This makes a wiring fault a higher-than-usual probability compared to other vehicles, especially if multiple injector codes are present.

Diagnostic Flowchart

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

Generation note: The 2012-2014 range covers two generations. The 2012 and 2013 models are part of the ninth generation. In 2014, Chevrolet sold both the ninth-generation body style as the "Impala Limited" (primarily for fleets) and the completely redesigned tenth-generation Impala. Both generations in this timeframe used the 3.6L LFX V6 engine, so the causes and diagnostics for P0201 are similar.

Symptoms You May Notice

• Check Engine Light is on
• Engine runs rough or misfires, especially at idle
• Noticeable loss of power and hesitation during acceleration
• Poor fuel economy
• Engine may stall
• Smell of raw fuel from the exhaust

Most Likely Causes

1. Faulty Cylinder 1 Fuel Injector 🔴 High Probability → Shop Fuel Injector Fuel injectors are a wear item. The internal coil windings can fail, creating an open or shorted circuit. As these are direct injection (GDI) injectors, they operate under high pressure and are located under the intake manifold, making replacement a more involved job.
   How to confirm: Disconnect the injector and measure its resistance with a multimeter. For the 3.6L LFX engine, the resistance should be between 1.2 and 1.8 Ohms. 🎬 Watch: Professional guide to testing LFX injector resistance and circuits. A reading outside this range or an infinite reading (open) indicates a bad injector. A more definitive test is to swap the cylinder 1 injector with another (e.g., cylinder 3), clear the codes, and see if the trouble code follows the injector (e.g., changes to P0203).
   Typical fix: Replace the faulty fuel injector. Due to the labor involved in removing the intake manifold, it is often recommended to replace all six injectors at the same time. 🎬 See this step-by-step walkthrough for replacing Impala fuel injectors.
   Est. part cost: $50-$150
2. Wiring Harness or Connector Issue 🟡 Medium Probability As detailed in GM TSBs #PIP4924D and #PI1067B, the LFX engine harness is known to chafe against multiple points. Common rub spots include the intake plenum, valve cover bolts, fuel lines, the side of the cylinder head, and the metal ECM bracket, leading to an open or short circuit.
   How to confirm: Visually inspect the wiring harness leading to the cylinder 1 injector for any signs of damage, melting, or chafing, paying close attention to the TSB-documented areas. Use a noid light to confirm the ECM is sending a pulse signal to the injector connector. Use a multimeter to check for continuity (no breaks in the wire) and for shorts to ground or power between the injector connector and the ECM connector.
   Typical fix: Repair the damaged section of wire with solder and heat-shrink tubing. Protect the repaired area with high-quality Tesa cloth tape and re-route or secure the harness with zip ties to prevent future contact.
   Est. part cost: $10-$50
3. Faulty Powertrain Control Module (PCM) ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This should be the last component to check after definitively ruling out the injector and wiring. If a noid light shows no pulse at the connector and the wiring is confirmed to be good from the injector to the PCM, the PCM's internal injector driver may have failed. This is more likely if multiple, unrelated injector codes are present.
   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 P0201 is present. Note any other codes, especially misfire (P0301) or other injector codes.
2. Locate Cylinder 1: On the transversely mounted 3.6L LFX in the Impala, the cylinders against the firewall (rear bank) are 1, 3, and 5 (passenger to driver side). The cylinders at the front of the car (front bank) are 2, 4, and 6. Cylinder 1 is on the rear bank, closest to the passenger side.
3. Inspect Wiring: Perform a thorough visual inspection of the wiring harness leading to the rear bank of injectors. Pay close attention to the known chafe points mentioned in TSBs: where the harness might rub against the intake plenum, valve cover bolts, and the ECM bracket.
4. Check for Pulse: Disconnect the injector connector. Use a noid light to check for a pulsing signal from the ECM while the engine is cranked. A flashing light indicates the ECM and wiring are attempting to command the injector to fire.
5. Test the Injector: If a pulse is present, the issue is likely the injector. Turn the ignition off, disconnect the injector, and measure its resistance with a multimeter. For the LFX engine, it should be between 1.2 and 1.8 ohms. An out-of-spec reading confirms a faulty injector.
6. Swap Injectors (Definitive Test): If you have access to the injectors, swap the cylinder 1 injector with an adjacent one on the same bank (like cylinder 3). Clear the codes and run the engine. If the code changes to P0203, the injector is confirmed to be the problem. If the P0201 code returns, the issue is in the wiring or ECM.
7. Test the Wiring Circuit: If no pulse was detected with the noid light, or if the code did not follow the swapped injector, test the wiring harness. Check for continuity from the injector connector back to the ECM connector. Also, check for a short to ground or a short to power on both wires in the circuit.
8. Suspect the ECM: If the injector and wiring are proven to be good, the Powertrain Control Module (PCM) is the likely culprit.

Parts You'll Likely Need

• Fuel Injector (OEM #ACDelco 12634126) — This is the most frequent point of failure for a P0201 code, as the internal coil can fail over time.
  Trusted brands: ACDelco, Bosch, Delphi, SKP
  OEM price range: $100-$180
  Aftermarket price range: $50-$120
• Fuel Injector Seal Kit (OEM #ACDelco 12644827) — The Teflon seals for these GDI injectors are single-use and must be replaced anytime an injector is removed to prevent high-pressure fuel leaks.
  Trusted brands: ACDelco, Fel-Pro
  OEM price range: $15-$25
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• P0301 — P0301 means 'Cylinder 1 Misfire Detected'. Since P0201 indicates a problem with fuel delivery to cylinder 1, a misfire on that same cylinder is an almost guaranteed consequence.
🎬 Watch: Diagnosing misfire codes on a 2014 Impala.
• P0202, P0203, P0204, P0205, P0206 — As noted in TSB #PIP4924D, seeing multiple injector circuit codes together strongly points to a larger issue, such as a damaged wiring harness common to multiple injectors or a problem with the PCM, rather than multiple injectors failing simultaneously.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: Addresses a Service Engine Soon light and misfire condition that can trigger numerous injector-related DTCs. Instructs technicians to inspect the fuel injector wiring harness for rub-through or internal wire opens.
• PI1067B: Specific to 2013-2014 models with the 3.6L LFX engine, this bulletin points to a potential wiring harness chafe point at the ECM bracket causing wire damage and setting various DTCs.

Platform-Specific Known Issues

• A Technical Service Bulletin for the 2012 model year (TSB #PIP4924D) notes that a Service Engine Soon light with a misfire may be accompanied by a wide range of injector DTCs, including P0201. This indicates a known potential for injector circuit issues on this platform.
• A related TSB for 2013-2014 models, #PI1067B, identifies a specific wiring harness chafe point at the metal ECM bracket, which can cause various DTCs including injector circuit faults.
• Owner forums and repair videos for the 3.6L LFX engine frequently cite the need to remove the upper intake manifold to access the fuel injectors, making the repair more complex than on port-injected engines.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (3.6L LFX GDI) — expected: 1.2 to 1.8 Ohms. Failure: A reading outside this range, or an open (OL) or shorted (near 0 Ohms) circuit.
• Injector Pulse Width (at idle) — expected: 1-5 milliseconds (ms). Failure: A value of 0 ms on cylinder 1 while others show a pulse would indicate the ECM is not commanding the injector, pointing to a wiring or ECM driver issue.
• Low-Side Fuel Pressure (Key On, Pump Running) — expected: 320-580 kPa (46-84 PSI). Failure: Pressure below this range could indicate a weak in-tank fuel pump, which could cause lean conditions but would not typically cause a P0201 circuit code.
• High-Side Fuel Rail Pressure (Engine Idling) — expected: 1.9-5.0 MPa (276-725 PSI). Failure: Pressure significantly outside this range points to issues with the high-pressure fuel pump or its sensor, which would typically set other codes like P228C, not P0201.

Scan Tool Commands That Help

• GDS2 (GM Tech Tool): Fuel Injector Balance Test — This is the most definitive test to confirm a faulty injector after verifying the electrical circuit. The tool commands each injector to fire and measures the corresponding drop in fuel rail pressure. If the pressure drop for cylinder 1 is significantly different (e.g., more than 20 kPa) from the others, it confirms a mechanical/flow issue with the injector itself.
• GDS2 (GM Tech Tool): Injector Test — This function allows a technician to command a specific injector to pulse repeatedly. It is used in conjunction with a noid light or oscilloscope to confirm that the ECM is sending a signal and that the signal is reaching the injector connector, which helps isolate a wiring fault from an ECM fault.

Wiring & Ground Locations

• G103 / G104 — G103 is on the front of the passenger side (Bank 1) cylinder head. G104 is on the rear of the driver's side (Bank 2) cylinder head.. These are primary engine grounds. While a bad ground here would likely cause multiple, more widespread issues, a loose or corroded connection at G103 (Bank 1) could theoretically cause erratic behavior for components on that bank, which includes cylinder 1.
• G112 — Located on the left rear of the engine for the 3.6L LFX.. This is another critical engine ground point. Verifying it is clean and tight is a key step when diagnosing any electrical fault on the engine.
• ECM Connector X1 — The main engine-side connector at the Engine Control Module, located in the engine bay near the firewall or airbox.. The control and power wires for the fuel injectors run from the ECM through this connector. Probing for continuity and checking for shorts at the specific pins for injector 1 at this connector allows a technician to test the entire wiring harness from the computer to the injector.

Real Owner Repair Stories

• GMTNation forum user (GM vehicle with similar engine platform and codes (P0201, P0301, P0300)) — Engine running rough and missing badly.
  ❌ Tried (didn't work) Swapped ignition coils between cylinders 1 and 3., Swapped spark plugs between cylinders 1 and 2.
  ✅ What actually fixed it The user performed continuity and resistance checks on the injector harness from the PCM connector, which tested good. Despite the wiring loom looking 'chewed on,' the wires were intact. The user decided to replace all six fuel injectors due to the difficulty of access and the uneven appearance of the plastic tips on the old injectors. This resolved the misfire and codes.

OEM Part Supersession History

• ACDelco 12634126 → ACDelco 12669384 — Standard part lifecycle update by the manufacturer. The new part is the current OE replacement.
  Heads up: The new part number (12669384) is the correct replacement for the original. Using the old part number if found as new-old-stock is acceptable, but the superseded number is preferred.

Model Year Variations Within This Range

• 2014: In 2014, Chevrolet sold both the 9th generation Impala as the 'Impala Limited' and the new 10th generation Impala. Both used the 3.6L LFX engine, but they are entirely different chassis with different body and interior electronics. While the engine-specific diagnosis for P0201 is nearly identical, a technician must be aware of which version they are working on, as harness routing and non-engine module locations will differ significantly.