🚨 Diagnostic Profile
Vehicle/Equipment Make: BUICK
Technical Description: Ignition Coil 2 Primary Feedback Circuit
This diagnostic code indicates that the Powertrain Control Module (PCM) has detected an irregular voltage signal on the primary control circuit for ignition coil #2. The PCM monitors a feedback signal from the coil driver to confirm that the coil is firing correctly in sync with the ignition command. When this feedback does not match the expected voltage pattern, it may point to a failing coil, damaged wiring harness, a corroded connector, or an internal PCM driver issue.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair requires the use of a diagnostic scan tool capable of reading live PCM data streams, as well as a digital multimeter to test circuit continuity, resistance, and voltage feedback signals. While replacing the ignition coil itself is often straightforward, accurately diagnosing whether the fault lies in the wiring harness, connector, or PCM driver circuit requires intermediate-level electrical diagnostic skills. No specialized module programming is typically required unless the PCM itself needs replacement.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the ignition coil #2 assembly, wiring harness, and electrical connector for signs of physical damage, corrosion, or melted insulation. Check for any burnt smell or discoloration around the coil connector, which could indicate overheating from an electrical short. Trace the wiring harness back toward the PCM, inspecting for chafing, pinched wires, or rodent damage along the route. Confirm that the coil connector is fully seated and locked into place.
Step 2: Diagnostic Verification
Connect a scan tool to the vehicle’s OBD-II port and retrieve all stored and pending diagnostic trouble codes, noting any additional codes related to misfires on cylinder 2 which often accompany this fault. Access live data stream parameters to monitor coil feedback voltage and ignition timing while the engine is running or cranking. Using a digital multimeter, back-probe the primary feedback circuit at the coil connector to measure voltage with the ignition on and while cranking, comparing readings to manufacturer specifications. Test the circuit for continuity and resistance between the coil and PCM connector to rule out an open or shorted wire. If readings are within specification at the harness but the fault persists, this may indicate an internal PCM driver failure.
Step 3: Resolution & Reset Process
If the ignition coil tests outside of specification or shows signs of internal damage, replace ignition coil #2 with an OEM or OEM-equivalent replacement part. If wiring or connector damage is found, repair or replace the affected harness section and ensure proper weatherproof sealing at all connections. After repairs are complete, clear the stored diagnostic trouble codes using the scan tool and perform a test drive while monitoring live data to confirm the feedback circuit now operates within normal parameters. If the PCM driver circuit is confirmed faulty through process of elimination, PCM replacement and programming may be required, followed by a full system relearn procedure.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Ignition Coil (Cylinder 2), Wiring Harness Repair Kit (if needed), OBD-II Scan Tool with Live Data Capability, Digital Multimeter, PCM (only if driver circuit fails internally)
Average Component Price: Ignition Coil: $40–$120 per coil (OEM pricing may run higher); Wiring Harness Repair: $50–$150 depending on extent of damage; PCM Replacement with Programming (if necessary): $400–$900
Estimated Labor Hours: Diagnostic Testing: 0.5–1.0 hour; Ignition Coil Replacement: 0.3–0.5 hour; Wiring Harness Repair: 1.0–2.0 hours; PCM Replacement and Programming (if required): 1.5–2.5 hours