P2DD5 — Fuel Injection Quantity B Lower Than Expected

Diagnostic algorithm

1. Retrieve freeze frame and all related DTCs. Note operating conditions when fault occurred.
2. Clear the code and attempt to reproduce while monitoring live data: commanded vs actual injection quantity, rail pressure, injector pulse width and fuel trims.
3. Check fuel rail pressure at idle and under load. If pressure is low or unstable, inspect/replace fuel filter, check fuel pump operation and supply, and test pressure regulator or metering valve.
4. Inspect wiring and connectors for all injectors on bank B. Repair any damage or corrosion. Wiggle test connectors while monitoring injector activity for changes.
5. Verify injector control signals with an oscilloscope or scope-capable scan tool. Confirm expected pulse width and injector driver current. If no driver output, trace back to ECM or driver circuit.
6. Perform an injector balance or flow test (active test if available) to confirm each injector on bank B flows within spec. Clean or replace injectors that fail flow or leakage checks.
7. If injectors test electrically OK but flow is low, consider ultrasonic cleaning or replacement. Follow safety steps when removing injectors and relieve fuel pressure before disconnecting.
8. Check fuel rail pressure sensor readings with a multimeter/scan tool. Compare sensor voltage to actual pressure; replace sensor if out of tolerance.
9. If wiring and injectors are good but commanded vs actual mismatch persists, investigate ECM injector driver outputs and perform ECU diagnostics or substitute a known-good module per manufacturer procedure.
10. After repairs, clear codes and road-test under the same conditions to confirm the fault does not return. Recheck fuel trims and injection quantity parameters.