OBD2 Car ScannerWhat does P0644 mean?
P0644 stands for Driver Display Serial Communication Circuit. The engine computer has found a fault in one of its own circuits or in a circuit it controls.
Powertrain codes cover the engine, transmission and emissions. When the car's computer sees a reading outside its normal range, it stores this code and may turn on a warning light on the dashboard.
Common causes
- Damaged wiring or a loose connector
- Low battery voltage or poor ground
- Faulty relay or actuator
- In rare cases, a faulty engine control module
What to do
- Read all stored and pending codes with a scanner. Several codes together often point to one cause.
- Note the freeze frame data (speed, temperature, load) recorded when the code was set.
- Inspect the wiring and connectors of the part named in the code for damage, corrosion or looseness.
- Fix the most likely and cheapest cause first, then clear the code and drive to see if it comes back.
Read this code from your own car
Plug in a cheap ELM327 adapter and the app shows every fault code, what it means and how to fix it.
Frequently asked questions
What does P0644 mean?
P0644 means “Driver Display Serial Communication Circuit”. It belongs to the computer and output circuits group: The engine computer has found a fault in one of its own circuits or in a circuit it controls.
Is it safe to drive with P0644?
You can usually drive carefully for a short time, but fix it soon to avoid further damage or higher fuel use.
How do I clear P0644?
Fix the cause, then clear the code with an OBD2 scanner or app. If the fault is still there, the code will come back.
Related codes
- P0640Intake Air Heater Control Circuit
- P0641Sensor Reference Voltage A Circuit Open
- P0642Sensor Reference Voltage A Circuit Low
- P0643Sensor Reference Voltage A Circuit High
- P0645A/C Clutch Relay Control Circuit
- P0646A/C Clutch Relay Control Circuit Low
- P0647A/C Clutch Relay Control Circuit High
- P0648Immobilizer Lamp Control Circuit
Code meanings can vary by manufacturer. This page is general guidance, not a repair manual. Always confirm the cause before replacing parts.