🚨 Diagnostic Profile
Vehicle/Equipment Make: BUICK
Technical Description: Injector Circuit Cylinder 5 Intermittent
This diagnostic trouble code indicates an intermittent electrical fault within the fuel injector circuit specifically assigned to cylinder 5. The Engine Control Module (ECM) has detected irregularities in the voltage or resistance signal to the injector driver circuit, which may cause misfires, rough idle, or reduced fuel economy. Because the fault is intermittent, it often points to a wiring harness issue, a corroded connector, or a failing injector rather than a constant hard failure.
🚨 Repair Difficulty Tier
Difficulty Rating: [Intermediate]
This repair requires the use of a diagnostic scan tool capable of reading live injector pulse data, along with a digital multimeter to test circuit resistance and voltage drop. While it does not require specialized module programming in most cases, it does demand a solid understanding of automotive wiring diagrams and injector driver circuits. DIY enthusiasts with intermediate electrical diagnostic experience can attempt this repair, but those unfamiliar with pinpoint testing should consult a professional technician.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the wiring harness and connector leading to the cylinder 5 fuel injector. Look for signs of chafing, melted insulation, corrosion, or loose terminal pins. Since the fault is intermittent, gently wiggle the harness and connector while monitoring for changes in connection stability. Also inspect the ECM connector for any corrosion or bent pins that could cause intermittent signal loss.
Step 2: Diagnostic Verification
Connect an OBD-II scan tool capable of accessing manufacturer-specific live data streams. Monitor the injector pulse width and compare cylinder 5 to the other cylinders for inconsistencies. Using a digital multimeter, perform a voltage drop test across the injector connector terminals with the key on, engine off, and again during cranking if possible. Check circuit resistance of the injector itself (typically between 11-18 ohms depending on injector type) and compare to manufacturer specifications. Perform a wiggle test while the multimeter is connected to catch intermittent opens or shorts.
Step 3: Resolution & Reset Process
If wiring damage or connector corrosion is found, repair or replace the affected harness section and reseal with weatherproof connectors. If the injector itself tests outside of resistance specifications or fails under load, replace the injector unit. After repairs are completed, clear the diagnostic trouble codes using the scan tool and perform a test drive while monitoring live data to confirm the intermittent fault does not return. In some cases, an ECM relearn or idle relearn procedure may be necessary after injector replacement to restore smooth engine operation.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Fuel injector (cylinder 5), wiring harness repair kit or connector pigtail, OBD-II diagnostic scan tool, digital multimeter.
Average Component Price: $45 – $180 for the injector (depending on engine type), $15 – $50 for wiring harness repair components.
Estimated Labor Hours: 1.0 – 2.5 hours for diagnosis and testing; an additional 0.5 – 1.5 hours if injector replacement or harness repair is required.