U0149
Lost Communication With Serial Data Gateway Module D
Communication network (gateway)
Generic OBD-II
Medium
What it means
U0149 means the network has lost communication with a serial data gateway module — the unit that passes messages between the vehicle's separate communication buses. Losing it can cut many modules off from each other, so you'll often see several warning lights and lost features at once. It's usually a power, ground, or bus wiring problem at the gateway.
Medium
Can I keep driving? Often drivable, but the gateway routes messages between buses — losing it can cut many modules off from each other, so expect several warning lights and lost features.
Common symptoms
What you'll notice
- Multiple warning lights on across different systems
- Several modules unreachable or reporting lost-communication codes
- Features that rely on cross-bus data stop working
- Serial data gateway module not responding to a scan tool
Common causes
Most likely first
- Loss of power or ground to the gateway moduleLikely
- Blown fuse feeding the gatewayCommon
- Corroded, damaged, or loose connectors and wiring at the gatewayCommon
- CAN bus wiring fault isolating the gateway from the networkLess often
- Failed serial data gateway moduleLess often
How to diagnose & fix
Work through it in order
- Scan all modules and note the pattern of lost-communication codes pointing back to the gateway.
- Check battery voltage and the gateway's fuses, power, and ground feeds first.
- Inspect the gateway's connectors and harness for corrosion, damage, or water intrusion.
- Test the bus wiring on each side of the gateway for opens or shorts.
- If power, grounds, and wiring are good, suspect the gateway — replace and program it as required, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0149?+
Usually yes mechanically, but with the gateway down, safety systems and warning displays may not work correctly, so have it diagnosed promptly.
Can I just clear U0149?+
You can, but it returns unless the gateway's power, ground, wiring, or the module itself is repaired.
Related codes
Often seen with U0149
Read & clear U0149 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