OBD-II code · Powertrain (generic)
P0644 Driver Display Serial Communication Circuit
The serial communication line to the driver display (instrument cluster, MIL/check-engine warning) shows a circuit fault. Driver may not see warning lights as expected.
Is it safe to drive with P0644?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHarness or driver fault
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Driver Display Communication
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.