U0073: Control Module Communication Bus A Off
A generic network and communication trouble code, same meaning on every brand.
Fix now, drive carefully
Drive gently to a shop - multiple systems can shut down together.
$60 - $1,500
typical repair range
35
NHTSA complaints mention this code
67,277
median mileage when reported, mi
Symptoms
- Several warning lights at once
- Multiple modules not responding to a scan tool
- Erratic gauges and disabled driver aids
Likely causes, most common first
- Short on the data bus wiring
- One module failing and jamming the bus
- Connector damage or water intrusion
- Failing battery or charging voltage
Read U0073 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
U0073 means the communication bus that lets the car's control modules talk to each other has shut down. Modern vehicles carry dozens of modules on a shared pair of wires, and when that pair is disturbed the modules stop hearing each other all at once - which is why the symptom is a dashboard full of lights rather than one specific fault.
Check battery and charging voltage before anything else. Low or unstable voltage upsets bus communication across the whole car and produces exactly this pattern, and it is far more common than a genuine wiring short. After that, disconnecting modules one at a time identifies a single unit that is jamming the bus.
Repair options and cost
Battery and charging test$60 - $150
Wiring or connector repair$150 - $500
Module replacement$500 - $1,500
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning U0073
“When driving, speedometer/RPM dial both go to 0. The "Service Stabilitrak" message comes on followed by the "Service Power Steering, Drive With Care" message. The check engine light will also sometimes appear. The transmission is also affected (jerking when changing gears, inability to accelerate properly, revving). Power steering goes in and out. Car doesn't feel safe to drive while it's happening. No triggers or commonalities known. Car goes back to normal when left off and turned back on. Code U0073 "Control Module Communication Bus 'A' Off" appeared with at home OBD2 scanner.”2017 Chevrolet Trax · Feb 2026
“ECM - Engine System code P0700 and TCM - Transmission System code U0073. The truck went in to first gear and wouldn't go over 5 MPH on the highway. The dealer is saying it can't be replicated but it's happened multiple times to the vehicle in the past week. The truck was taken to the dealership and inspected but they claim nothing is wrong. The check engine light came on as well as the aforementioned codes.”2023 GMC Sierra 1500 · Nov 2025
“2018 Camry with very low mileage (appx 38,000) and had all its required services done, suddenly had a check engine light. Less than a minute after that, "Coolant Temp High - Stop where it's safe" message popped up. Service center indicated it was a failed water pump (diagnostic codes P26CB71, U0073, U016387, U0163, P26CB). Coolant was gone. Multiple users for 2018/2019 have reported this water pump failure on r/Camry [XXX] Does not seem safe to have a car go from no problem to near catastrophic engine failure with virtually no warning INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)”2018 Toyota Camry · Aug 2025
Show 7 more owner reports
“The problems listed in my vehicle are the following - U0073: Control Module Communication Bus A Off - U0100: Lost Communication With Engine Control Module - U0121: Lost Communication with Electronic Brake Control Module - U0140: Lost Communication With Body Control Module - P0700: Transmission Control Module Requested MIL Illumination I believe this is due to a bad design in the wiring. Also the electric brake vacuum broke which is a common problem.”2020 Chevrolet Malibu · Jul 2024
“I started my vehicle this morning and backed out of my driveway and when I went to shift out of reverse there was a sudden and violent jolt through the car and the check engine light came on and and the car information center displayed "Service Power Steering" with actual loss of power steering for approximately 45 seconds message cleared and my power steering returned to normal. Then "Service Stabilitrak" displayed on the information center and disappeared shortly after. Engine light remains on with fault codes P0700, U0100, and U0073 during diagnostic scan.”2020 Chevrolet Trax · Mar 2023
“UNKNOWN . Stabilitrak , power steering drive with care, and steering assist is reduced drive with care light turned on . I was on the freeway with my newborn and the car was slowly giving out and suddenly stopped while in the carpool lane . Took it to the car dealer and did a diagnostics and codes u100,u0101, u0415, and u0073 popped up . This is the second time this same exact thing has happened to me same messages popped up so I took it to the dealer and codes p0300 came out and p050D came out . This malfunction could have caused a serious injury to myself or my family .”2018 Chevrolet Malibu · Apr 2022
“Car will throw codes p0700/u0073/u1000 - looses engine power, check stabilitrak lights up, check engine light comes on. Car will buck, odometer/rpm gauge/temp gauge will become erratic. Took to the chevy dealership, unable to replicate problem. Unsafe to drive. Doesn't happen daily - sometimes car will not start/unable to drive.”2011 Chevrolet Equinox · Jan 2019 · 78,000 mi
“All ip warning lamps illuminated, loss of power, stalling, gage fluctuation, intermittent door lock operation. Vehicle was in motion on highway when this occurred. Error codes include u0073, u0121m u0101, u0242 ( from dealership analysis). Cause unknown. Vehicle has been in dealership more than 7 weeks without cause of problem not isolated. Technician stated crackling sound when grasping wiring in dashboard area. Loss of communication between control module and various components occurs within one (1) to five (5) seconds. Chevrolet issued tech bulletin #08-07-30-021e. Dealership has followed this bulletin without correcting the problem.”2008 Chevrolet Tahoe · Jan 2018 · 42,286 mi
“Traction control warning light flashed on and off several times. When it was on the steering became difficult. Tried to pass a slow moving truck. Engine rpms when up but vehicle did not accelerate. Check engine light came on. Had mechanic check code and the following codes show up u0121, u0073 and u0121 he stated a product safety notice #14515b had been issued for this problem. Contacted a chevy dealer and was told this was not a recall issue.”2010 Chevrolet Traverse · Sep 2015 · 120,000 mi
“I had ABS, and brake lights came on. The speedometer, odometer and a/c has stopped working without reason. Dealer found u0073 trouble code and I had the replace ABS actuator assembly which includes ABS pump and ecu. From the research that I made online, I have found out that many 07-10 camry users have the same problems with their ABS system. A new actuator assembly costs over 3000 dolares and they are manufactured by bosch. I believe that toyota is hiding the problem because a recall cost on this particular matter will be a lot higher. An example of the problem was shown in the following youtube video: https://www.youtube.com/watch?v=rdtgabjrfds”2007 Toyota Camry · Mar 2014 · 60,000 mi
Cars that report U0073 most often
Based on mentions of this code in NHTSA owner complaints.
2007 Toyota Camry4 mentions in complaints2011 Chevrolet Equinox2 mentions in complaints2023 GMC Sierra 15002 mentions in complaints2011 Chevrolet Tahoe1 mentions in complaints2013 Buick Regal1 mentions in complaints2017 Chevrolet Bolt1 mentions in complaints2016 Chevrolet Colorado1 mentions in complaints2013 Subaru XV Crosstrek1 mentions in complaints2020 Chevrolet Malibu1 mentions in complaints2023 Chevrolet Malibu1 mentions in complaints2011 Chevrolet Silverado 15001 mentions in complaints2006 Chevrolet Cobalt1 mentions in complaints
Frequently asked questions
Can I drive with U0073?
Drive gently to a shop - multiple systems can shut down together.
How much does it cost to fix U0073?
Typical US repair costs range from $60 for the simplest fix (battery and charging test) to $1,500 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to U0073. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.