Engine/Injector Control Module Communication Error
Findings, check these first
- Open communication link between ECM and IDM
- Corroded IDM connector
- Failing IDM
- Low system voltage
- Chafed link wiring
Standard procedure
- Verify IDM power and ground
- Inspect the IDM connector for corrosion
- Test link continuity between modules
- Check system voltage
- Repair wiring or replace the IDM
Code lookup
Type a code above, or start from a symptom or a common code.
Press / to jump to the box. Ford-enhanced powertrain, body, chassis and network codes. Generic P0xxx codes live on OBD Codes List.
Sources and review
Review: checked against the recorded source material.
- OBDII.pro: P1668 Ford definition
live reference page (obdii.pro)
Supports: Ford-family meaning for P1668: PCM - IDM Communications Error
Fetched directly. obdii.pro is a publisher independent of the engine-codes family.
- P1668 FORD Code: Meaning, Causes, and Symptoms | OBD2 Codes
live reference page (obd2-codes.co)
Supports: Ford meaning for P1668: PCM – IDM Communications Error
Fetched directly. obd2-codes.co phrasing matches the engine-codes family, so it counts as one publisher.
Last updated 2026-09-06.
Report a correction for P1668. Include your vehicle, the issue and a source if you have one.
This fault is part of the Ford fuel and ignition codes guide. It covers the family and the order to check it.