U0019
Low Speed CAN Communication Bus
Communication network (low-speed CAN)
Generic OBD-II
Medium
What it means
U0019 is a fault on the low-speed CAN communication bus — the network that links body and comfort modules such as lighting, HVAC, locks, and the instrument cluster. When the bus is disrupted, those modules can't reliably share data, so features misbehave and warning lights appear. The engine usually still runs, but the cause is normally wiring, a ground, or a failed module on the bus.
Medium
Can I keep driving? Usually yes — the engine typically runs, but body and comfort features on the low-speed bus (lighting, HVAC, locks, cluster warnings) may act up or drop out.
Common symptoms
What you'll notice
- One or more warning lights on, sometimes several at once
- Body/comfort features misbehave (HVAC, interior lighting, door locks, windows)
- Instrument-cluster gauges or indicators read wrong or go blank
- Lost-communication (U01xx) codes stored in several modules
Common causes
Most likely first
- Damaged, corroded, or loose low-speed CAN wiring or connectorsLikely
- A failed module on the bus dragging the whole network downCommon
- Poor ground or unstable power supply to a bus moduleCommon
- Water intrusion in a connector or moduleLess often
- Faulty gateway module bridging the busesLess often
How to diagnose & fix
Work through it in order
- Scan every module and record all stored U-codes to see which modules dropped off the bus.
- Inspect the low-speed CAN wiring, connectors, and grounds for damage or corrosion.
- Check battery and charging voltage — low or unstable voltage upsets the bus.
- Measure bus resistance/voltage and isolate a failed module by disconnecting suspects one at a time.
- Repair the wiring or replace the confirmed faulty module, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0019?+
Often for short trips, but if warning lights, gauges, or lighting are affected, get it checked soon — a flaky bus can disable safety-related features without warning.
Can I just clear U0019?+
You can, but if the wiring or module fault is still present it returns, often with more lost-communication codes across modules.
Related codes
Often seen with U0019
Read & clear U0019 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX