C8 Code U0401
Thread Starter
3rd Gear
Joined: Apr 2017
Posts: 3
Likes: 0
C8 Code U0401
I started my C8 yesterday ( first time of the day ) and found the check engine light illuminated. I pulled out of the garage and let her get to temperature. I noticed no issues in it running. I contacted On Star and had them run a diagnostic test. They reported Code U0401 which is ~ An issue has been detected in the vehicle with a vehicle network communication code. The network provides a communications link between systems inside the vehicle and when the network is disrupted a code can be set. If vehicle functionality is impacted please seek service soon. Has anyone had this issue? Action to be taken is listed as NONE?
Any information would be greatly appreciated.
Any information would be greatly appreciated.
2nd Gear
Joined: Mar 2024
Posts: 2
Likes: 8
U0401
A little late to providing a response. I only am as I just went through a scare of having the engine light pop on my 24' Z06, with only 401 miles on it. In my situation, I had just removed my front bumper off the car to install a new carbon flash splitter and dive planes. I ended up starting the car twice during the process to move the vehicle in and out of the garage. There was a sensor that was disconnected for this and it threw the code. Once everything was reconnected, I did a quick 10 mile drive, parked it over night. The engine light was off. The code was still in the system to check.
2nd Gear
Joined: Aug 2024
Posts: 2
Likes: 0
Same U401 code for me on my 2024 ZO6 with only 180 miles on it
I just had the exact same code show up on my Z06 today and mine only has 180 miles on it. I’m hoping it’s just a communications failure because the car seems perfect
Racer
Joined: Sep 2017
Posts: 324
Likes: 236
From: Cave Creek, Arizona
Started my car after sitting for about a month (on vacation), and got these codes. Only thing i can see is the check engine light. Called onstar who said nothing is wrong but then got their email which shows there clearly was something going on.
2024 Z06 @3000 miles on it with no issues so far......(except this)
TCM - Transmission System
U0401
Vehicle network communication code. The network provides a communications link between systems inside the vehicle and when the network is disrupted a code can be set. If vehicle functionality is impacted please seek service soon.
No action needed
ECM - Engine System
P0700
Transmission Control Module Requested Malfunction Indicator Lamp Illumination. The DTC is an informational DTC. The DTC indicates an emission related DTC set in the Transmission Control Module.
Service within 7 days
2024 Z06 @3000 miles on it with no issues so far......(except this)
TCM - Transmission System
U0401
Vehicle network communication code. The network provides a communications link between systems inside the vehicle and when the network is disrupted a code can be set. If vehicle functionality is impacted please seek service soon.
No action needed
ECM - Engine System
P0700
Transmission Control Module Requested Malfunction Indicator Lamp Illumination. The DTC is an informational DTC. The DTC indicates an emission related DTC set in the Transmission Control Module.
Service within 7 days
Race Director
Joined: Mar 2007
Posts: 11,463
Likes: 8,635
Started my car after sitting for about a month (on vacation), and got these codes. Only thing i can see is the check engine light. Called onstar who said nothing is wrong but then got their email which shows there clearly was something going on.
2024 Z06 @3000 miles on it with no issues so far......(except this)
TCM - Transmission System
U0401
Vehicle network communication code. The network provides a communications link between systems inside the vehicle and when the network is disrupted a code can be set. If vehicle functionality is impacted please seek service soon.
No action needed
ECM - Engine System
P0700
Transmission Control Module Requested Malfunction Indicator Lamp Illumination. The DTC is an informational DTC. The DTC indicates an emission related DTC set in the Transmission Control Module.
Service within 7 days
2024 Z06 @3000 miles on it with no issues so far......(except this)
TCM - Transmission System
U0401
Vehicle network communication code. The network provides a communications link between systems inside the vehicle and when the network is disrupted a code can be set. If vehicle functionality is impacted please seek service soon.
No action needed
ECM - Engine System
P0700
Transmission Control Module Requested Malfunction Indicator Lamp Illumination. The DTC is an informational DTC. The DTC indicates an emission related DTC set in the Transmission Control Module.
Service within 7 days
Racer
Joined: Sep 2017
Posts: 324
Likes: 236
From: Cave Creek, Arizona
U0401 is one of a family of codes that indicate a comms problem somewhere and the dealer will have to figure it out, if it does not go away. The other code P0700 is just the code for setting the light - it provides no additional information other than that there was request to set the light.
I'm assuming if i reset the code myself it will come back if there is a problem....I may try that on Sunday..
Race Director
Joined: Mar 2001
Posts: 19,983
Likes: 6,782
From: Bonneville Salt Flats
It sounds like a glitch in the system to me, something that once cleared may never return... or, maybe again the next time the car is started. Welcome to the world of rolling computers (and yes, I've seen this sort of thing myself). 
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Racer
Joined: Sep 2017
Posts: 324
Likes: 236
From: Cave Creek, Arizona
hopefully it never returns……..
Racer
Joined: Oct 2006
Posts: 339
Likes: 68
From: BUFFALO GROVE ILLINOIS
Hello UA.
Had the exact same scenario with my Z on the road at 3700 miles. No symptoms. Car was running fine.
Called my trusted service guy (Elvis at Libertyville Chev Illinois) with codes from OnStar.
He advised it will take up to 7 ignition cycles to clear.
It did.
At 6000 miles all is great.
Had the exact same scenario with my Z on the road at 3700 miles. No symptoms. Car was running fine.
Called my trusted service guy (Elvis at Libertyville Chev Illinois) with codes from OnStar.
He advised it will take up to 7 ignition cycles to clear.
It did.
At 6000 miles all is great.
CF Community Team
Joined: Apr 2016
Posts: 14,198
Likes: 7,469
From: Pittsburgh
2025 C6 of the Year Finalist - Unmodified
2024 C6 of the Year Finalist - Unmodified
2023 C6 of the Year Finalist - Unmodified
2022 C6 of the Year Finalist - Unmodified
2021 C6 of the Year Finalist - Unmodified
Keep up with those warranties folks!
Racer
Joined: Sep 2024
Posts: 383
Likes: 398
Yeah, I've had it pop up twice in 5300 miles, and lots of track time. I swear, I think sometimes when you cold start the car to move it and then turn it back off quickly, it doesn't like that either. I always have a Blue Driver USB tool to check and clear these dumb codes, so I don't have to cycle it a bunch before it clears itself.
Car runs fine, no issues. Maybe when I take it in for the 7500 trans filter change, I'll have them look at it to see if any new updates are needed, but I'm not worried about it.
Car runs fine, no issues. Maybe when I take it in for the 7500 trans filter change, I'll have them look at it to see if any new updates are needed, but I'm not worried about it.
Burning Brakes
Joined: Mar 2012
Posts: 752
Likes: 281
From: West Palm Beach, FL
The U0401 code on your C8 Corvette indicates "Invalid Data Received from Engine Control Module (ECM)". This is a communication error within the vehicle's CAN (Controller Area Network) system.
What Causes Code U0401?
- Temporary Network Glitch:
- Sometimes, a brief loss of communication between modules can trigger the code without affecting performance.
- Battery/Voltage Issues:
- Low battery voltage or fluctuations (e.g., weak battery, infrequent driving) can disrupt communication signals.
- Faulty Wiring/Connections:
- Loose or corroded connections in the CAN bus wiring harness.
- Faulty Control Module:
- Rare, but the Engine Control Module (ECM) or another module may not send/receive proper data.
Heel & Toe
Joined: Jul 2025
Posts: 18
Likes: 18
Yeah, I've had it pop up twice in 5300 miles, and lots of track time. I swear, I think sometimes when you cold start the car to move it and then turn it back off quickly, it doesn't like that either. I always have a Blue Driver USB tool to check and clear these dumb codes, so I don't have to cycle it a bunch before it clears itself.
Car runs fine, no issues. Maybe when I take it in for the 7500 trans filter change, I'll have them look at it to see if any new updates are needed, but I'm not worried about it.
Car runs fine, no issues. Maybe when I take it in for the 7500 trans filter change, I'll have them look at it to see if any new updates are needed, but I'm not worried about it.