AutoCodes – Ford – P1668 Ford

P1668 Ford Code - PCM - IDM Communications Error

Quick Answer

P1668 Ford indicates PCM - IDM Communications Error. Common causes include Open fuse, Faulty Injector Driver Module (IDM) Relay, Injector Driver Module (IDM) Relay harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1668 Ford indicates PCM - IDM Communications Error.
Common causes: Common causes include Open fuse, Faulty Injector Driver Module (IDM) Relay, Injector Driver Module (IDM) Relay harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 22,550

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 08, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1668 Ford Description

OBDII Code P1668 Ford - PCM - IDM Communications Error - AutoCodes.com — P1668 Ford Code - PCM - IDM Communications Error

What does this mean?

What are the Possible Causes of the DTC P1668 Ford?

Open fuse
Faulty Injector Driver Module (IDM) Relay
Injector Driver Module (IDM) Relay harness is open or shorted
Injector Driver Module (IDM) Relay circuit poor electrical connection
Faulty Injector Driver Module (IDM)

How to Fix the DTC P1668 Ford?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1668 Ford code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1668 Ford Code

1. What does the OBDII code P1668 mean on a Ford vehicle?

P1668 indicates a PCM (Powertrain Control Module) to IDM (Injector Driver Module) communication error, meaning the modules are not properly exchanging data.

2. What are the common symptoms of code P1668 on a Ford?

Symptoms may include engine misfires, rough idling, reduced power, difficulty starting, or the engine not starting at all.

3. What causes the P1668 code to appear on a Ford?

Common causes include faulty wiring or connectors between the PCM and IDM, a malfunctioning IDM, a defective PCM, or issues with the power or ground circuits.

4. Can a blown fuse cause the P1668 code on a Ford?

Yes, a blown fuse in the IDM circuit can disrupt communication between the PCM and IDM, triggering the P1668 code.

5. How do I diagnose the P1668 code on my Ford vehicle?

Start by checking the wiring and connectors between the PCM and IDM for damage or loose connections. Verify power and ground to both modules, and test the IDM and PCM for proper functionality.

6. Can I drive my Ford with the P1668 code active?

Driving with the P1668 code is not recommended, as it can lead to poor performance, engine damage, or a complete engine failure.

7. How do I fix the P1668 code on a Ford?

Repairs may include fixing damaged wiring or connectors, replacing a faulty IDM or PCM, or addressing issues in the power or ground circuits.

8. Can a software update resolve the P1668 code on a Ford?

In rare cases, reprogramming or updating the PCM software may resolve the communication error if it is caused by a software glitch.

9. How much does it cost to repair the P1668 code on a Ford?

The cost varies depending on the underlying issue, ranging from $50–$150 for minor wiring repairs to $500 or more for module replacement and reprogramming.

10. Do I need to replace both the PCM and IDM for the P1668 code?

Not necessarily. Only replace the PCM or IDM after confirming that one of them is faulty through proper diagnostics.