Engine-Codes - Generic - P0866

P0866 - TCM Communication Circuit High

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What is this?
Table of contents

P0866 Possible Causes

  • Faulty Transmission Control Module (TCM)
  • Transmission Control Module (TCM) harness is open or shorted
  • Transmission Control Module (TCM) circuit poor electrical connection
  • Faulty Engine Control Module (ECM)

How do I fix code P0866?

Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Cost of diagnosing the P0866 code

Labor: 1.0

The cost of diagnosing the P0866 code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P0866 Meaning

The Engine Control Module (ECM) monitors the Transmission Control Module (TCM). The ECM sets the OBDII when there is a problem communicating with the TCM.

P0866 More Information

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