Practical checks and shop questions for P0602/P0603/P0605/P0606; save evidence before replacing parts.
This is a non-invasive owner checklist, not an OEM repair procedure or permission to drive.
This reference supports the stated topic only. Model, model year, equipment, current rule or individual vehicle conditions may differ; check the original source before acting.
Read the Ford original: 1999 Powertrain Control/Emissions Diagnosis DTC descriptions Source date: document date not recorded; research checked: 2026-11-01.
Codes in this diagnostic topic
These codes share a system-level checklist, but their distinct numbers and meanings are shown below. A code here does not prove a particular vehicle has every listed fault. Use the exact code row and full scan.
| Code | Meaning | Vehicle scope |
|---|---|---|
| P0602 | Control-module programming error | Exact vehicle scope unverified |
| P0603 | Keep-alive memory fault | Exact vehicle scope unverified |
| P0605 | Read-only memory fault | Exact vehicle scope unverified |
| P0606 | Control-module processor fault | Exact vehicle scope unverified |
Save the evidence first
- Exact module/code and suffix
- Power interruptions and software history
- All companion codes
Safe owner checks
- Retain scan evidence; avoid disconnecting the battery as a diagnostic shortcut.
Questions for a qualified technician
- Does a current calibration bulletin, supply problem or genuine module failure explain the code?
- For the Giulia bulletin, are both ECUs included in the approved update?
Common wrong turns
- A processor code is not automatic authorization to buy a PCM.
- Programming is not a beginner DIY reset.
Confirm the repair
- Verify software identity and associated faults after professional repair.
Sources and scope
- Ford — 1999 Powertrain Control/Emissions Diagnosis DTC descriptions Document: date not recorded · Research checked: 2026-11-01
- Stellantis — 18-005-25 Document: 2025-02-08 · Research checked: 2026-11-01
Research snapshot: 2026-11-01. Source documents may have newer revisions. Verify current instructions and VIN eligibility with the manufacturer.