P0265 on 2013-2016 Cadillac ATS: Cylinder 2 Injector Circuit High Causes and Fixes

What's Unique About the 2013-2016 Cadillac ATS

For this generation of Cadillac ATS, the P0265 code is frequently not a failed injector but a problem with the engine's wiring harness. General Motors issued multiple Technical Service Bulletins (TSBs) highlighting that a wiring concern at or near the #2 fuel injector connector is a common cause for this specific code, often accompanied by a misfire code like P0300 or P0302. The issue often stems from the harness rubbing against engine components like the intake manifold, valve cover bolts, or other brackets, eventually wearing through the wire's insulation and causing a short or open circuit.

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)
• Engine misfire, which may feel like a shake or stumble (especially at idle)
• Rough or uneven idle
• Hesitation or loss of power during acceleration
• Reduced fuel economy
• Raw fuel smell from the exhaust

Most Likely Causes

1. Wiring or Connector Fault at Injector #2 🔴 High Probability As documented in GM TSBs #PIP5386 and #PIP4924D, the wiring harness is known to chafe or develop faults near the #2 injector on these vehicles. The harness can rub against the corner of the cylinder head, valve cover bolts, or other engine brackets, causing a short to voltage or an open circuit.
   How to confirm: Visually inspect the wiring harness leading to the cylinder 2 fuel injector. Look for any signs of rubbing, chafing, melting, or broken wires. Unplug the connector and check for corrosion, backed-out pins, or damage. Wiggle the harness with the engine running to see if the misfire changes.
   Typical fix: Repair the damaged section of the wire using a weatherproof splice. If the connector is damaged, it should be replaced with a new pigtail connector (e.g., ACDelco PT2160). Wrap the repaired area in anti-abrasion tape to prevent future damage.
   Est. part cost: $15-$50
2. Faulty Cylinder 2 Fuel Injector 🟡 Medium Probability → Shop Fuel Injector Direct injection fuel injectors operate under high pressure and can fail internally, causing an electrical fault (short or open in the coil winding).
   How to confirm: If wiring is confirmed to be good, test the injector. Use a multimeter to check the resistance across the injector's terminals; it should be within the manufacturer's specified range (typically 11-14 ohms for port injection, but can vary for direct injection). The most definitive test is to swap the cylinder 2 injector with another cylinder's injector (e.g., cylinder 4). If the code changes to P0271 (Cylinder 4 Injector Circuit High), the injector is faulty.
   Typical fix: Replace the faulty fuel injector. For direct injection engines (2.0L Turbo, 3.6L V6), the Teflon seals must also be replaced, which requires special tools. It is often recommended to replace all injectors on a high-mileage engine. 🎬 See this step-by-step guide for replacing your fuel injectors.
   Est. part cost: $90-$215
3. Powertrain Control Module (PCM) Failure ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This should only be considered after the wiring and injector have been ruled out. A professional technician can use an oscilloscope to test the injector driver circuit signal from the PCM. If the signal is absent or incorrect despite good wiring, the PCM is likely at fault.
   Typical fix: The PCM would need to be replaced and programmed to the vehicle's VIN.
   Est. part cost: $400-$1000

Diagnosis Steps

1. Read all stored and pending trouble codes from the ECM with an OBD-II scanner.
2. Visually inspect the entire wiring harness and connector for cylinder #2's fuel injector. Pay close attention to areas where the harness might rub against the intake manifold, valve cover, or engine brackets. Look for chafing, melting, or corrosion.
3. If the wiring looks good, disconnect the injector and check for 12V power on one pin with the key on. The other wire is the control wire from the ECM.
4. Use a noid light to verify that the injector is receiving a pulse signal from the ECM while cranking the engine. A steady light or no light indicates a wiring or ECM problem.
5. If a signal is present, use a multimeter to check the resistance of the fuel injector. Compare the reading to the manufacturer's specifications (e.g., typically 11.4-13.4 Ω for many GM applications). A reading that is significantly high or low indicates a failed injector.
6. As a definitive test, swap the cylinder 2 injector with an injector from another cylinder (e.g., cylinder 4). Clear the codes and run the engine. If the fault code moves to the new cylinder (P0271), the injector is bad.
7. If the code remains on cylinder 2 after swapping the injector, the problem is confirmed to be in the wiring or the ECM.
8. If all other possibilities are exhausted, the issue may be with the injector driver circuit in the ECM, which requires professional diagnosis, likely with an oscilloscope.

Parts You'll Likely Need

• Fuel Injector Connector Pigtail (OEM #ACDelco PT2160) — If the wiring is damaged at the connector, or the connector lock is broken, replacing the pigtail is the standard repair.
  Trusted brands: ACDelco, Dorman, Standard Motor Products (S-824)
  OEM price range: $25-$50
  Aftermarket price range: $13-$30
• Fuel Injector (OEM #12634126 (3.6L V6), 12627093 (2.5L), 12662564 (2.0L Turbo)) — If the injector itself has failed internally (shorted or open coil), it will need to be replaced. Part numbers vary by engine.
  Trusted brands: ACDelco, Bosch, Hitachi
  OEM price range: $105-$200
  Aftermarket price range: $80-$150

Related Codes That Often Appear With This One

• P0300 — This is a 'Random Misfire' code. It is cited in TSB #PIP5386A along with P0265, indicating the injector fault is causing a general misfire that the ECU detects across multiple cylinders.
• P0302 — This is a 'Cylinder 2 Misfire' code. Since P0265 points to a problem with cylinder 2's injector, it's very common for the PCM to also detect the resulting misfire in that specific cylinder.
🎬 Watch: DIY troubleshooting for a Cadillac ATS P0302 misfire.
• P0264 — This code is for 'Cylinder 2 Injector Circuit Low'. It is mentioned alongside P0265 in TSBs, suggesting that wiring issues can cause either a high or low circuit fault depending on the nature of the damage (e.g., short to ground vs. short to power).

Technical Service Bulletins (TSBs) & Recalls

• PIP5386A: Communicates diagnostic steps for P0264 or P0265 with P0300, explaining inspection and repair.
• PIP5386: Notes that P0265 with P0300 may be due to a wiring concern at the #2 fuel injector.
• PIP4924D: Lists P0265 as one of many possible injector circuit codes that may be found.

Platform-Specific Known Issues

• TSB #PIP5386A points directly to a potential wiring concern at the #2 fuel injector as the cause for P0265 or P0264, often accompanied by a P0300 misfire code. The bulletin advises technicians to remove the intake manifold to properly inspect the harness for chafing against the engine block or other components.
• TSB #PIP4924D also lists P0265 among a large group of injector codes that can be set due to various issues, indicating a broader potential for injector circuit faults on these platforms.
• Owner forums frequently discuss this code. A common real-world failure point is the harness rubbing through on a sharp edge of the intake manifold or a bracket near the #2 cylinder.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance — expected: 11.4 - 13.4 Ohms (Ω) is a common range for GM injectors. Direct Injection (2.0T, 3.6L) may have lower resistance, around 0.5 - 2.0 Ohms (Ω).. Failure: A reading of infinite ohms (OL) indicates an open coil. A reading significantly lower than spec indicates a shorted coil.
• Injector Connector Voltage (Key On, Engine Off) — expected: One pin should show battery voltage (approx. 12.6V). The other pin (control wire) should also show battery voltage as it's waiting to be grounded by the ECM.. Failure: No voltage on the power supply wire indicates a problem upstream (fuse, relay, wiring). No voltage on the control wire could indicate a short to ground.
• Injector Pulse Width (at idle, via scan tool) — expected: Typically 2-4 milliseconds (ms) for a warm engine at idle.. Failure: A significantly longer pulse width on cylinder 2 could be the ECM attempting to compensate for a separate issue, while a value of 0 would indicate the ECM has shut down the injector due to the circuit fault.

Scan Tool Commands That Help

• GM GDS2 (or high-end bidirectional scanner): Injector Test / Cylinder Power Balance — This function allows the technician to individually disable each fuel injector while the engine is running. When the cylinder #2 injector is commanded off, if there is no change in engine RPM or smoothness, it confirms the fault is isolated to that cylinder's fuel delivery. This helps verify the location of the misfire without swapping parts.
• GM GDS2 (or high-end bidirectional scanner): Fuel Injector Balance Test — This automated test measures the pressure drop in the fuel rail as each injector is pulsed. A cylinder with a clogged or malfunctioning injector will show a smaller pressure drop than the others. While less common for a 'Circuit High' code, it can help rule out a mechanical injector issue.

Wiring & Ground Locations

• G104 — On the 3.6L V6, this ground is located on the front of the right cylinder head. On other engines (2.0L, 2.5L), it is typically on the lower rear of the cylinder head.. This is a primary engine ground point. While not directly for the injector circuit itself, a poor connection here can cause electrical noise and voltage irregularities that may affect the ECM's sensors and drivers, potentially leading to incorrect fault codes.
• Injector #2 Connector — On the 2.0L Turbo and 2.5L engines, cylinder #2 is the second from the front. On the 3.6L V6, cylinder #2 is the front-most cylinder on the driver's side (left bank).. This is the primary location for the fault. The TSBs specifically call out chafing of the harness near this connector, where it may rub against the intake manifold, cylinder head, or brackets.
• ECM/PCM Connector — The Engine Control Module is typically located in the engine bay, often near the battery or firewall.. If wiring from the injector to the ECM is confirmed good, a continuity and pin-drag test should be performed at the ECM connector to rule out a bad terminal connection before condemning the module itself.

OEM Part Supersession History

• 12627093 → 12662564 — Part has been updated by the manufacturer. The new part is the current service replacement.
  Heads up: The original part number 12627093 for the 2.5L engine has been replaced by 12633913, 12662570, and finally 12662564. When replacing, it is recommended to use the latest part number. Mixing old and new design injectors is generally not advised.