P0644 OBD-II Trouble Code: Driver Display Serial Communication Circuit

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0644 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0644 code

P0644 is a diagnostic trouble code (DTC) for "Driver Display Serial Communication Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $69.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$69.99$20.00
Toyota$69.99$20.00
BMW$69.99$20.00
SCHEDULE P0644 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P0644 code definition

The P0644 trouble code detects a communication error between multiple control modules

What the P0644 code means

The P0644 code is a standard OBD-II trouble code that notes a control module communication problem. The powertrain control module (PCM) is in constant communication with the other control modules, which include the climate control module, anti-lock brake control module, transmission control module, and traction control module, among others. If the PCM notes a failure of communication between itself and another control module, or if the PCM is unable to control a supporting control module, then the P0644 code will be noted.

What causes the P0644 code?

Causes for the P0644 trouble code include:

  • Faulty electrical connection in the PCM
  • Defective PCM driver
  • Loose control module ground strap
  • Broken ground wire
  • Damaged electrical components in the controller area network (CAN) bus
  • In rare cases, a defective PCM or CAN bus

What are the symptoms of the P0644 code?

The P0644 trouble code will usually be accompanied by an illuminated Check Engine Light. It is common for the vehicle to have engine and transmission performance issues, such as delayed acceleration, harsh shifting, rough idling, and frequent stalling at idle. Reduced fuel efficiency is also common.

How does a mechanic diagnose the P0644 code?

The P0644 code will be diagnosed using an OBD-II trouble code scanner. A certified mechanic will use the scanner to view the freeze frame data and gather information about the P0644 code. Additional trouble codes will also be searched for, and, if found, should be addressed in the order in which they are displayed on the scanner. The mechanic will then need to reset the trouble codes, restart the vehicle, and see if the P0644 code remains detected. If the code has disappeared, then an intermittent error or an inaccurate detection are likely to blame.

If the code remains detected, then the mechanic will begin by visually inspecting the electrical components in the PCM and CAN bus. Any loose or corroded connectors, shorted wires, or blown fuses will require replacement. The ground strap and ground wire will then need to be tested.

Next, the mechanic can hook up a specialized diagnostic CAN scanner, which provides detailed information about the control modules and circuitry. This scanner can be used to pinpoint where the problem that is causing the P0644 code is coming from.

Whenever the mechanic replaces any part, the codes should again be reset, the vehicle again restarted, and the P0644 code searched for. This helps the mechanic identify as soon as the error has been resolved.

Common mistakes when diagnosing the P0644 code

The most frequently made mistakes when diagnosing the P0644 trouble code come from a failure to properly follow the OBD-II diagnosis protocol. It is imperative that technicians always comply with the protocol, as this helps ensure a speedy and accurate diagnosis.

Numerous other trouble codes are usually present when the P0644 code is detected. Often, these codes are simply a reaction to a communication failure created by the P0644 code. If the codes are addressed out of order, a reactionary code may be erroneously inspected, and unnecessary repairs may take place.

How serious is the P0644 code?

A vehicle with the P0644 trouble code will likely still be drivable, though there will usually be noticeable drivability issues. An inspection should be scheduled as soon as the code is detected.

What repairs can fix the P0644 code?

Repairs for the P0644 trouble code are:

Additional comments for consideration regarding the P0644 code

It is uncommon for the P0644 trouble code to occur because of a defective PCM or CAN bus. Mechanics should always inspect all other potential causes before presuming that there is a PCM or CAN bus failure. If either of these two components does need to be replaced, it will also need to be reprogrammed.

Need help with a P0644 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

trouble codes
Check Engine Light
P0644

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0644 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

4,240

Rating Summary
3,884
174
45
26
111
3,884
174
45
26
111
Rusty

Rusty

20 years of experience
263 reviews
Rusty
20 years of experience
Great no complaints!
2013 CHEVROLET CRUZE - CHECK ENGINE LIGHT IS ON INSPECTION - ARLINGTON, TEXAS
Rigoberto

Rigoberto

8 years of experience
517 reviews
Rigoberto
8 years of experience
This guy is extremely knowledge. He definitely knows his stuff. Everyone hopes to find a reliable mechanic that they can trust for all their cars. I found my mechanic. I cant say enough about Rigobertos expertise. Its why i will always go back to him. Thank you so much.
2002 TOYOTA RAV4 - CHECK ENGINE LIGHT IS ON - CHICAGO, ILLINOIS
Charles

Charles

14 years of experience
176 reviews
Charles
14 years of experience
He was great and he do great work
2004 AUDI A6 QUATTRO - CHECK ENGINE LIGHT IS ON - WASHINGTON, DISTRICT OF COLUMBIA
Joseph

Joseph

24 years of experience
351 reviews
Joseph
24 years of experience
Joseph is great! Early to the appointment, professional, knowledgeable and diagnosed the problem with-in minutes. He is truly a life-saver! I'd be happy to have him work on my car anytime.
2010 FORD ESCAPE - CHECK ENGINE LIGHT IS ON - HOUSTON, TEXAS

More related articles

How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...

Related questions

Q: VSC and Traction control lights on after wheel alignment. Unable to reset/recalibrate

A faulted sensor like the steering angle sensor can cause these systems to malfunction. A steering angle reset is required with an alignment on these vehicles and involves a procedure that includes disconnecting the battery. If you'd like a fresh...

Q: The car hesitates at higher speeds, check engine light on

You need to have the Check Engine Light code diagnosed to see if you have a problem. I feel the person that checked you car was trying to sell you a service that you may not need instead of looking...

Q: i have this code for my 2008 nissan sentra po725 readng the symptoms i have none car runs perfect in fact like about 9 months ago

I am unable to tell you exactly what is going on with your vehicle without more information, but I can give you the information I have available on the diagnostic trouble codes (DTC's) that you have listed. The P0725 relates...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com