P0268 — - High Cylinder 3 Cylinder Chain

Diagnostic algorithm

1. Retrieve all stored codes and freeze frame data; note related misfire or cam/crank correlation codes.
2. Check oil level and quality; top up or change oil if severely degraded. Clear codes and test drive to see if code returns.
3. Visually inspect wiring and connectors to cam/crank sensors and phaser solenoid; wiggle-test for intermittent faults.
4. Use a scope or scan tool to compare cam and crank sensor waveforms and verify phase/relationship at idle and varying RPMs. Look for missing pulses or shifted timing.
5. Command VVT/phaser solenoid (if available) and observe mechanical response and oil control activity.
6. If signals indicate timing slip or incorrect phase, remove timing cover to inspect chain, guides, tensioner, sprockets and phaser. Check chain for stretch, guide wear, or damaged teeth.
7. Perform compression or leak-down test on cylinder 3 if a mechanical damage or persistent misfire is suspected.
8. Repair or replace failed components (sensors, wiring, tensioner, guides, chain, phaser) as indicated by findings. After repair, perform any required cam/crank relearn or ECU adaptations and verify the repair on road test.
9. Clear codes and confirm the fault does not return under same conditions that previously triggered it.