P0202 on 2010-2014 Cadillac SRX: Injector Circuit Malfunction Causes and Fixes

What's Unique About the 2010-2014 Cadillac SRX

For the second-generation Cadillac SRX, a P0202 code should be taken seriously, especially in light of GM's own technical service bulletins. TSB #PIP4924D specifically addresses a condition where the Service Engine Soon light is on with a misfire and a wide range of injector circuit codes (P0201-P0206), including P0202. This suggests a potential for systemic wiring harness issues on this platform, such as chafing or bad grounds, not just isolated injector failures. A forum post on a similar GM 3.6L engine showed multiple injector codes (P0202, P0204, P0206) were caused by a single corroded ground connection for that entire cylinder bank.

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)
• Rough idle or stalling
• Engine hesitation or stumbling on acceleration
• Reduced engine power and 'limp mode'
• Decreased fuel economy
• A noticeable fuel smell from the exhaust
• Engine vibration

Most Likely Causes

1. Faulty Fuel Injector (Cylinder 2) 🔴 High Probability → Shop Fuel Injector Injectors are wear items and can fail electrically (internal coil shorts or opens) over time. This is a common failure on the GM High Feature V6 engine family.
   How to confirm: Swap the cylinder 2 injector with an adjacent one on the same bank (e.g., cylinder 4). If the code changes to P0204, the injector is faulty. Alternatively, test the injector's resistance with a multimeter; it should be within a specific range, typically around 11-14 ohms. A reading of 0 ohms indicates a short, and an infinite reading (OL) indicates an open circuit.
   Typical fix: Replace the failed fuel injector. It is often recommended to replace all injectors on a high-mileage engine, especially since accessing them requires removing the intake manifold. 🎬 Watch: 3.6L intake removal and fuel injector replacement walkthrough
   Est. part cost: $80-$180
2. Wiring Harness or Connector Issue 🟡 Medium Probability As noted in TSB #PIP4924D, this platform may be susceptible to wiring issues. Wires can chafe against engine components like the camshaft cover or brackets, or the connector pins can become corroded, loose, or broken.
   How to confirm: Visually inspect the wiring harness leading to the cylinder 2 injector for any signs of damage, melting, or chafing. Pay close attention to where the harness bends or makes contact with the engine. Unplug the connector and check for corrosion or bent/loose pins. Use a 'noid light' to confirm the injector is receiving a pulse signal from the PCM. If multiple injector codes for the same bank are present (e.g., P0202, P0204, P0206), check the common power feed and ground connections for that bank.
   Typical fix: Repair the damaged section of the wiring harness or replace the injector connector pigtail. If a common ground is corroded, clean and secure the connection.
   Est. part cost: $15-$40
3. Faulty Powertrain Control Module (PCM) ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This should be the last resort after all other possibilities (injector, wiring) have been definitively ruled out by a professional. This is confirmed by testing the injector driver signal directly at the PCM connector. If a noid light doesn't flash at the injector but the wiring is confirmed to be good from the PCM to the injector, the PCM's internal driver may have failed.
   Typical fix: Replace and reprogram the PCM.
   Est. part cost: $400-$1000

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner. Note P0202 and any other codes present, like P0302.
2. Identify Cylinder 2. On the transverse 3.0L/3.6L V6 in the SRX, the engine banks are: Bank 1 (cylinders 1, 3, 5) is the rear bank, closer to the firewall. Bank 2 (cylinders 2, 4, 6) is the front bank, closer to the radiator. Cylinder 2 is the cylinder on the front bank closest to the passenger side (front right of the engine).
3. Perform a 'swap test'. This requires removing the upper intake manifold. Swap the fuel injector from cylinder 2 with the one from cylinder 4 (the middle cylinder on the same bank). Reassemble, clear the codes, and drive the vehicle. If the code returns as P0204, the fuel injector is confirmed to be the problem.
4. If the P0202 code returns after the swap, the issue is in the wiring or PCM. Inspect the wiring harness to the cylinder 2 injector for any visible damage, paying special attention to areas where it might chafe on the cam cover or other brackets.
5. Use a 'noid light' to test the injector connector. With the intake removed for access, plug the light into the connector for cylinder 2 and crank the engine. A rhythmic flashing light indicates the PCM is sending a signal, and the wiring is likely good. No flash points to a wiring or PCM problem.
6. If the noid light does not flash, check for power (around 12V) on one pin of the connector with the key on. If power is present, the issue is in the ground control wire going back to the PCM. If no power is present, there is a break in the power supply wire or a blown fuse.
7. If all wiring tests pass and the injector has been ruled out, the problem may be with the injector driver circuit within the PCM, which requires professional diagnosis.

Parts You'll Likely Need

• Fuel Injector (OEM #12638530 (for 3.0L/3.6L LLT), 12669384 (supersedes 12638530), 12634126 (for 2012+ 3.6L LFX)) — This is the most common failure point for a P0202 code after wiring is checked. Part number may vary by specific engine (LLT vs LFX).
  Trusted brands: ACDelco, Bosch, Standard Motor Products, Hitachi
  OEM price range: $100-$180
  Aftermarket price range: $50-$130
• Fuel Injector Connector Pigtail — If the wiring inspection reveals a damaged, corroded, or melted connector at the injector, it will need to be replaced.
  Trusted brands: ACDelco, Dorman
  OEM price range: $25-$40
  Aftermarket price range: $15-$30
• Upper Intake Manifold Gasket Set — These are single-use gaskets that must be replaced anytime the intake manifold is removed to access the fuel injectors.
  Trusted brands: ACDelco, Fel-Pro
  OEM price range: $40-$70
  Aftermarket price range: $20-$50

Related Codes That Often Appear With This One

• P0302 — P0302 means 'Cylinder 2 Misfire Detected'. If the injector circuit has a fault (P0202), the injector won't deliver fuel, causing the cylinder to misfire. This is an expected companion code.
• P0201, P0203, P0204, P0205, P0206 — If multiple injector circuit codes are present, it strongly suggests a wiring harness problem common to all injectors (like a shared power or ground wire) or a PCM driver issue, as mentioned in TSB #PIP4924D.

Technical Service Bulletins (TSBs) & Recalls

• PIP4924D: This bulletin addresses a Service Engine Soon light and misfire condition accompanied by a wide array of diagnostic trouble codes related to the fuel injector circuits. It suggests investigating common wiring or connection issues when multiple codes are present.

Platform-Specific Known Issues

• Technical Service Bulletin PIP4924D was issued for these vehicles, noting that multiple injector circuit codes (P0201-P0206, etc.) can appear with a misfire, pointing towards a potential wiring harness or electrical connection problem rather than individual component failure.
• The 3.0L (LF1) and 3.6L (LLT/LFX) V6 engines require removal of the upper intake manifold to access the fuel injectors, which significantly increases the labor time and cost of repair compared to engines with more accessible fuel rails.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance (3.0L LF1 / 3.6L LLT Port Injection) — expected: 11-14 Ohms. Failure: A reading of OL (infinite) indicates an open coil, while a reading near 0 Ohms indicates a short. Any significant deviation suggests a failing injector.
• Fuel Injector Coil Resistance (3.6L LFX Direct Injection) — expected: 1.5 - 1.6 Ohms. Failure: These are low-impedance injectors. A reading of OL (open) or a significant deviation from this very narrow range indicates a failed injector coil.
• Injector Circuit Voltage (Key On, Engine Off) — expected: ~12 Volts (Battery Voltage). Failure: No voltage on the power supply pin of the injector connector points to a blown fuse or an open in the power feed wire.
• Injector Circuit Voltage (Engine Running) — expected: Steady Battery Voltage. Failure: A low or fluctuating voltage on the cylinder 2 injector circuit while the engine is running (when compared to a known good cylinder) points to a circuit fault or a failing PCM driver.

Scan Tool Commands That Help

• GDS2 / Tech2: Cylinder Power Balance — Used to confirm which cylinder is misfiring. The scan tool disables injectors one by one and measures the RPM drop. If disabling cylinder 2 causes little or no change in RPM, it confirms that cylinder is not contributing power.
• GDS2 / Tech2: Injector Test / Active Fuel Injector Tester (AFIT) — This is an automated function that commands each injector to fire and measures the corresponding fuel pressure drop. It can identify a clogged or electrically faulty injector without requiring a manual swap.

Wiring & Ground Locations

• Bank 2 Injector Power/Ground — The Bank 2 injectors (2, 4, 6) are on the front side of the engine, closest to the radiator. The wiring harness runs across the front of the engine and is susceptible to chafing against the intake plenum, valve cover bolts, and other brackets.. As per TSB PIP4924D, harness chafing is a known issue. A short or open in the harness for cylinder 2 will directly cause a P0202. If multiple codes for Bank 2 are present (P0202, P0204, P0206), a fault in the shared power feed or ground for that bank is highly likely.
• Injector Connector C106 (example) — On similar GM V6 platforms, a large connector (like C106) serves as a junction for the injector harness before it splits to individual injectors. Tracing the cylinder 2 control wire back from this connector to the PCM is a key step in diagnosing a wiring fault.. A corroded or loose pin in this intermediate connector can cause an intermittent open circuit for a single injector, leading to a P0202 code that is difficult to trace directly at the injector or PCM.

Real Owner Repair Stories

• YouTube video by Christopher Kleman (2005 Cadillac SRX 3.6L (similar LLT engine and diagnostics)) — Check Engine Light with codes P0202 and P0302. The misfire was intermittent; it would often start after the car was driven, stopped, and restarted.
  ❌ Tried (didn't work) Swapped fuel injectors between cylinders; the fault remained on cylinder 2., Visually inspected the wiring harness under the intake manifold for damage., Performed a full continuity and resistance check of the wiring from the main harness connector (C106) to the injector, which tested good.
  ✅ What actually fixed it The final diagnosis was a failed injector driver (transistor) inside the Engine Control Module (ECM). All wiring and the injector itself were confirmed to be good, leaving the ECM as the only possible cause. The fix required replacing or remanufacturing the ECM.

OEM Part Supersession History

• 12638530 → 12669384 — Standard part revision by GM.
  Heads up: This injector is for the 2010-2011 3.0L LF1 and 3.6L LLT port-injected engines. It is NOT compatible with the 2012+ LFX engine.
• 12642128 → 12634126 — Standard part revision by GM.
  Heads up: This injector is for the 2012-2014 3.6L LFX direct-injection engine. It is NOT compatible with the earlier LF1/LLT engines.

Model Year Variations Within This Range

• 2010-2011: These years primarily used the 3.0L LF1 and 3.6L LLT V6 engines. These are port-injected engines and use high-impedance fuel injectors (e.g., PN 12638530) with a resistance of around 11-14 Ohms. The ECM is typically a Bosch unit.
• 2012-2014: The standard engine became the 3.6L LFX V6. This is a direct-injection engine with a composite intake manifold and integrated exhaust manifolds. It uses low-impedance injectors (e.g., PN 12634126) with a resistance of around 1.5-1.6 Ohms and a different ECM (typically Delphi). Parts are not interchangeable between LFX and LLT/LF1 engines.