What are the common causes of P0644?

A wiring fault on the driver display serial bus. Corrosion at the display connector. A failed driver display module. A wiring fault between the display and the PCM. A faulty PCM output.

Check for other communication codes. Inspect the display serial bus wiring and connectors. Check the display module power and ground. Look for a module pulling the bus down. Repair the serial bus if the display does not communicate. Clear the code and retest.

P0644

Driver Display Serial Communication Circuit

System: Computer output circuits (P code)
Lamp: Check Engine Light
Category: Powertrain - Computer and Auxiliary Controls

What it means

P0644 means Driver Display Serial Communication Circuit.

Check these first

A wiring fault on the driver display serial bus
Corrosion at the display connector
A failed driver display module
A wiring fault between the display and the PCM
A faulty PCM output

What to do next

Check for other communication codes
Inspect the display serial bus wiring and connectors
Check the display module power and ground
Look for a module pulling the bus down
Repair the serial bus if the display does not communicate
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.