P219E — 3 - Fuel ratio imbalance

Diagnostic algorithm

1. Retrieve and record freeze frame and live data (STFT/LTFT, O2/wideband traces) for bank 3.
2. Clear the code and perform an immediate test drive while monitoring trims and sensor signals to re-create the fault.
3. Visually inspect intake, vacuum lines, injector harness and connectors on bank 3 for damage or disconnection.
4. Perform a smoke test of the intake to find external leaks feeding bank 3.
5. Measure fuel rail pressure and flow under load; compare to specification. Repair fuel pump/pressure regulator or replace filter as needed.
6. Perform an injector balance or flow test for cylinders on bank 3; clean or replace injectors that are out of tolerance.
7. Monitor upstream O2/wideband sensor response; if sensor is slow, stuck or biased, consider sensor replacement after confirming no flow/pressure issues.
8. Check MAF output and cleaning; replace if signal inconsistent with airflow and engine rpm.
9. Inspect exhaust manifold/egress for leaks upstream of the sensors which can bias oxygen readings.
10. Repair identified faults (vacuum leak, injector, fuel pressure, sensor or wiring). Clear codes and retest to ensure no recurrence and that trims normalize.