AutoCodes – Generic – P1766

P1766 Code - CAN Communication Bus Off

Quick Answer

Controller Area Network (CAN) communication is a parallel circuit to interchange information among each unit. Common causes include Controller Area Network (CAN) Bus, CAN comm line circuit open/short, Faulty Transfer Case Control Unit (TCCU). 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: P1766 indicates CAN Communication Bus Off.
Common causes: Common causes include Controller Area Network (CAN) Bus, CAN comm line circuit open/short, Faulty Transfer Case Control Unit (TCCU).
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 11,368

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 Aug 07, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1766 Description

Controller Area Network (CAN) communication is a parallel circuit to interchange information among each unit. CAN communication can share much information with units faster and more efficiently by using specified language.
CAN-High line is twisted with CAN-Low line as a purpose of preventing noise. The Diagnostic Trouble Code (DTC) P1766 is related to the communication line between ECM and Transfer Case Control Unit (TCCU) is set when CAN signal from ECU can’t be received for more than 1 sec or ECU internal error occurred. If failure is detected TCCU prohibits the ITM control.

OBDII Code P1766 - CAN Communication Bus Off - AutoCodes.com — P1766 Code - CAN Communication Bus Off

What does this mean?

What are the Possible Causes of the DTC P1766?

Controller Area Network (CAN) Bus
CAN comm line circuit open/short
Faulty Transfer Case Control Unit (TCCU)
Faulty ECU
Faulty Anti-Lock Brake System (ABS) Module

How to Fix the DTC P1766?

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 P1766 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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Information for Specific Makes

P1766 Ford — Shift Solenoid 'D' Performance
P1766 Hyundai — CAN Communication Bus Off
P1766 Kia — CAN Communication Bus Off
P1766 Mazda — Shift Solenoid 'D' Performance

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.