P2691 — Cylinder 6 Injector Data Incompatible

Diagnostic algorithm

1. Retrieve all stored codes and freeze frame data. Note symptoms and operating conditions when fault occurred.
2. Visually inspect the cylinder 6 injector connector and wiring for damage, corrosion, bent pins or oil intrusion. Repair as required.
3. Measure static injector 6 resistance; compare to factory specification. If out of range, replace the injector.
4. Backprobe the injector connector and check for proper supply voltage, ground and command signal while cranking/idle. Verify battery voltage at the connector.
5. Use an oscilloscope or noid light to observe injector 6 waveform; compare to a known-good cylinder. Look for missing pulses, abnormal current draw or irregular waveform shapes.
6. Swap injector 6 with a known-good injector from another cylinder (if feasible) and see if the fault follows the injector. If the code follows, replace the injector.
7. If the code remains on cylinder 6 after swapping injectors, perform harness continuity and resistance checks between injector 6 connector and the ECM. Repair any opens/shorts.
8. Check for and apply any available ECM software updates or injector coding procedures. Reprogram injector ID/calibration if vehicle requires injector coding after replacement.
9. If wiring and injector are good, suspect ECM driver fault; confirm with manufacturer diagnostic procedures before replacing ECM.
10. After repairs, clear codes, perform a road/test drive cycle and verify that the code does not return and drivability is restored.