Chevrolet U0078
GMNA) • Chinese language translation errors for utility rate schedule type and engine sound • Japanese language translation was incomplete • Korean language translation error for t
Quick answer
For the verified applicability, U0078 is associated with a Chevrolet software update bulletin, not a confirmed component failure description. The supplied evidence identifies improved diagnostic algorithms for U0078 Trailering and separate infotainment translation/display concerns.
This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.
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1. What does U0078 mean?
For the verified applicability, U0078 is associated with a Chevrolet software update bulletin, not a confirmed component failure description. The supplied evidence identifies improved diagnostic algorithms for U0078 Trailering and separate infotainment translation/display concerns.
2. Technical explanation
The verified source is GM bulletin 21-NA-188, published through NHTSA on June 24, 2022. Its supplied summary states that the update improves Ethernet DTC diagnostic algorithms for U1008, U18B4, and U0078 Trailering. The same bulletin summary also lists non-GMNA translation issues, including Chinese utility-rate-schedule and engine-sound translations, incomplete Japanese translation, and a Korean translation error related to target charge completed. The supplied record title/meaning includes truncated translation text; it does not establish a standard standalone technical definition for U0078.
3. What system is affected?
Not yet established by verified evidence. The bulletin summary references Ethernet DTC diagnostic algorithms and Trailering, while also listing infotainment display and translation concerns.
4. How serious is this code?
Unknown. The supplied verified evidence does not assign a severity level.
5. Symptoms you may notice
- Not yet established by verified evidence for U0078 specifically.
- The bulletin summary references a Trailer app condition in which some trailer profiles can cause the display to go blank and then return to the Home screen.
- The bulletin summary references translation issues in Chinese, Japanese, and Korean.
6. Possible causes
- Not yet established by verified evidence. The verified bulletin describes improved diagnostic algorithms for U0078 Trailering but does not identify a failed part, wiring fault, or other root cause.
7. Can I still drive the vehicle?
Unknown. The supplied verified evidence does not establish whether driving is safe with U0078.
8. Can I charge the vehicle?
Unknown. The supplied verified evidence does not establish whether charging is safe with U0078.
9. What you can safely do
- Record the exact warning messages, display behavior, and whether a trailer or Trailer app profile was in use.
- Arrange Chevrolet service to check for the applicable software update and to read stored diagnostic information.
- Do not attempt high-voltage, network, or module repairs yourself.
10. Step-by-step troubleshooting
- Check whether the vehicle matches the verified applicability: 2022 Chevrolet Bolt EV in the US.
- Provide the service department with bulletin number 21-NA-188 and the stored code U0078.
- Have service confirm whether the bulletin's software update applies to the vehicle configuration. Further diagnostic steps are not established by the supplied evidence.
11. When to contact service
Contact a Chevrolet dealer or qualified Chevrolet service provider, particularly if U0078 is stored or infotainment/trailering functions are affected. Ask them to review GM bulletin 21-NA-188.
12. What the service center may check
- Confirm vehicle eligibility for GM bulletin 21-NA-188.
- Check for the bulletin-described software update.
- Review stored DTCs, including U0078, U1008, and U18B4 where present. The supplied bulletin summary identifies these codes together for diagnostic-algorithm improvements.
13. Possible repair or resolution
- The verified bulletin indicates a software update intended to improve Ethernet DTC diagnostic algorithms for U0078 Trailering.
- Whether this update resolves a particular vehicle's U0078 condition is not established by the supplied evidence.
14. Affected vehicles
- Chevrolet Bolt EV · 2022 · US
15. Related TSBs / service bulletins
- GM/NHTSA manufacturer communication 21-NA-188, published June 24, 2022: https://static.nhtsa.gov/odi/tsbs/2022/MC-10215627-0001.pdf
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Verified official source: NHTSA Manufacturer Communication PDF 10215627, GM bulletin 21-NA-188, published June 24, 2022.
19. Frequently asked questions
Does the verified evidence define U0078 as a high-voltage battery or charging fault?
No. The supplied evidence does not establish that U0078 is a high-voltage battery or charging fault.
Is there a verified service bulletin related to U0078?
Yes. Bulletin 21-NA-188 states that it improves Ethernet DTC diagnostic algorithms for U0078 Trailering, along with U1008 and U18B4.
Does the bulletin apply to a 2022 Chevrolet Bolt EV in the United States?
The supplied applicability record identifies the 2022 Chevrolet Bolt EV in the US. Final eligibility should be confirmed by Chevrolet service.
Does the verified evidence confirm that the vehicle can be driven or charged?
No. Driving and charging status are not established by the supplied evidence.