U0034: Vehicle Communication Bus A (-) Low
System
Network Communication
What Does U0034 Mean?
U0034 is a diagnostic trouble code indicating: Vehicle Communication Bus A (-) Low. This code relates to the network communication system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
What To Do Next
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1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
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2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
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3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.
Related Codes
U0029
Vehicle Communication Bus A Performance
U0030
Vehicle Communication Bus A (+) Open
U0031
Vehicle Communication Bus A (+) Low
U0032
Vehicle Communication Bus A (+) High
U0033
Vehicle Communication Bus A (-) Open
U0035
Vehicle Communication Bus A (-) High
U0036
Vehicle Communication Bus A (-) shorted to Bus A (+)
U0037
Vehicle Communication Bus B