P1C46 — Cylinder 6 Contribution/Balance — Below Threshold

Diagnostic algorithm

1. Retrieve freeze frame and full scan data; record related codes and misfire counts for cylinder 6.
2. Perform a visual inspection: check spark plug, coil pack/boot, wiring and connectors for cylinder 6. Replace or swap with a known good unit if suspect.
3. Swap the ignition coil and/or spark plug from cylinder 6 with another cylinder. Clear codes and test-run: if the fault follows the coil/plug, replace that component.
4. Monitor injector pulse width for cylinder 6 with a scope or scan tool. Swap injector with another cylinder to check if the fault follows the injector.
5. Check fuel pressure at the rail to ensure proper supply. If pressure is low or fluctuating, diagnose fuel pump/regulator and fuel filter.
6. Perform a compression test and/or leak-down test on cylinder 6 and compare to other cylinders. Low values indicate mechanical issues (valves, piston rings, head gasket).
7. Inspect for intake manifold gasket leaks or vacuum leaks near cylinder 6 (use smoke test or spray test where safe and appropriate).
8. Verify camshaft/crankshaft timing and VVT operation. Check for timing chain/belt skip, actuator failure, or incorrect cam/crank correlation.
9. Check secondary ignition waveform and look for weak spark or misfires; examine ignition system ground and battery voltage.
10. Check MAF/MAP and fuel trim data to identify systemic lean/rich conditions that could affect one cylinder.
11. If mechanical, repair cylinder-specific hardware (valve service, head gasket, piston/ring work) as indicated by test results.
12. After repairs, clear codes and perform a road/drive cycle to confirm cylinder contribution returns to normal and no new codes appear.