U0019 code meaning
Low Speed CAN Communication Bus
What U0019 means
U0019 is the general fault slot for the low-speed CAN, the slow body network serving doors, lighting, locks and comfort electronics. Two physical forms exist: the two-wire fault-tolerant CAN of ISO 11898-3, which NXP's TJA1055 runs at up to 125 kBd and keeps alive on one wire after a single break or short, and the one-conductor low-speed GMLAN that GM runs at 33.33 kbit/s. FCA names U0019 CAN B Bus; on the 2015 Ram ProMaster the BCM logged U0019-01 (general electrical failure) with a lit MIL, cured by a BCM reflash under bulletin 08-230-22. Mercedes-Benz lists U001988 among the codes behind false anti-theft alarms in 2019-25 models and has supply, ground and CAN lines to the overhead panel checked. Comfort functions suffer rather than driveability.
U0019 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0019
- Comfort functions such as locks, lighting or windows fail or act erratically
- Anti-theft alarm triggers without obvious reason
- Lost-communication codes for several body modules
- MIL on in some vehicles (FCA ProMaster 2015)
Common causes of U0019
- Most likelyDamaged low-speed bus wiring or corroded, loose connector pins
- PossiblePoor supply or ground at a module on the body bus
- PossibleModule software logging the code without a real fault (FCA ProMaster BCM)
- Less likelyFaulty module or transceiver disturbing the low-speed bus
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Low speed CAN wiringBody control moduleModule connector
What each part of U0019 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 19 | The exact fault in that area. |
What to do next
- Note U0019 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0019
What does U0019 mean?
U0019 means "Low Speed CAN Communication Bus". U0019 is the general fault slot for the low-speed CAN, the slow body network serving doors, lighting, locks and comfort electronics. It is a generic code, so it means the same on every make.
Is it safe to drive with U0019?
U0019 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0019 fail an emissions test?
U0019 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U0019 to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will U0019 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.