U0221
NetworkModule Communicationhigh severityLost Communication With Zone Module B
What U0221 Means
The network lost communication with zone module B. Electrical functions handled by that zone may fail.
Symptoms
- Multiple systems not working
- Warning lights on dash
- Intermittent electrical faults
Common Causes
- Faulty zone module B
- Harness or connector damage
- Loss of power or ground
- Fuse failure
Diagnostic Steps
- Retrieve stored codes
- Verify module power and ground
- Inspect wiring and connectors
- Check CAN communication
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Community Confirmed Fixes
No confirmed fixes yet for this code. Be the first to contribute!
Submit a FixFound a Fix for U0221?
Help other technicians by sharing what worked on your vehicle.
Submit Your Fix