P1339 — Cylinder 3 ignition fail malfunction

Diagnostic algorithm

1. Connect a capable scan tool and record stored/freeze-frame data and any additional active codes. Note conditions when code set (RPM, load, temp).
2. Clear codes and attempt to reproduce. Confirm P1339 returns and capture live misfire counters for cylinder 3.
3. Visually inspect coil, plug, wiring, and connector for cylinder 3. Repair any obvious damage or corrosion before further tests.
4. With engine off, remove spark plug from cylinder 3. Inspect plug for fouling, oil, or damage. Replace with correct type if suspect.
5. Swap the ignition coil/igniter from cylinder 3 with another cylinder. If the fault follows the coil, replace the coil/igniter.
6. If coil swap does not move the fault, test coil primary/secondary resistance and compare to spec. Use an oscilloscope if available to check waveform under cranking/starting.
7. Check wiring continuity and for shorts to ground or battery between coil connector and ECU. Wiggle test harness while monitoring live data for changes.
8. Verify fuel injector for cylinder 3 is operating (listen for click, measure pulse, or use a noid light). Check injector resistance and perform a spray test if available.
9. Perform a compression or leak-down test on cylinder 3 to rule out mechanical causes of misfire.
10. Check camshaft and crankshaft sensors and timing/correlation data if misfires are random or if cam/crank sync faults are present.
11. If all circuits and components check good, consider ECU/ignition module failure or intermittent wiring; consult manufacturer Technical Service Bulletins and consider module replacement or professional diagnostics.
12. Safety: follow manufacturer procedures, disconnect battery when performing electrical repairs, and avoid live ignition coil testing with hands or unshielded tools.