P0644

Driver Display Serial Communication Circuit

Q: Is it safe to drive with P0644?

The car will run, but losing gauges and warning lights is a real safety issue — you may miss a temperature or oil warning. Get the display fixed soon.

Q: Can I just clear P0644?

It clears, but returns while the communication link is broken. Repair the wiring or display to fix it properly.

Module communication Generic OBD-II High

What it means

P0644 means the ECM has lost or corrupted serial communication with the driver display (the instrument/message display). The engine still runs, but the display can go blank, freeze, or show wrong readings, so you may lose gauges and warning messages. It usually traces to the communication wiring, a connector, or the display module.

High

Can I keep driving? Usually drivable — the engine runs, but the driver display may go blank or show wrong data, so you can lose gauges and warnings. Treat missing instrumentation as a safety concern.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Driver display blank, frozen, or showing incorrect information
Missing gauges or warning messages
Intermittent display dropouts

Common causes

Most likely first

Damaged or shorted wiring in the serial communication circuitLikely
Loose or corroded connectors at the display or ECMCommon
Failed driver display / instrument clusterCommon
Poor power or ground to the display moduleLess often
ECM fault (checked last)Less often

How to diagnose & fix

Work through it in order

Scan all modules for related communication (U-series) codes to see which end has dropped off the bus.
Inspect the wiring and connectors between the ECM and the driver display for damage, corrosion, or a poor fit.
Verify the display module has good power and ground.
Repair the communication wiring; replace the display/cluster if it's confirmed unresponsive with good wiring.
Clear the code and confirm the display shows correct data.

FAQ

Quick answers

Is it safe to drive with P0644?+

The car will run, but losing gauges and warning lights is a real safety issue — you may miss a temperature or oil warning. Get the display fixed soon.

Can I just clear P0644?+

It clears, but returns while the communication link is broken. Repair the wiring or display to fix it properly.

Read & clear P0644 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX