U0037: Vehicle Communication Bus B

Generic fault on vehicle communication bus B (second physical bus, e.g. body CAN, comfort CAN, or LIN). One or more nodes cannot communicate.

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

Most likely causes

• Wiring or node fault on bus B
• Gateway module routing CAN messages incorrectly
• CAN terminating resistor (120 Ω) drifted out of spec

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the battery and terminals, and read the codes from all control modules with a multi-system scanner
2. Identify which control module is not responding and check its fuses, power supply, and grounds
3. Disconnect add-on accessories, such as alarms or trackers, and read the codes again
4. Inspect the network connectors for moisture or bent pins
5. Measure the network's resistance and signal using the manufacturer's wiring diagram

Good to know

• Repair difficulty: hard
• It can trigger limp mode.

What each character of U0037 means

• U: Communication network
• 0: Generic code: same on every make
• 0: Subsystem depends on the code range
• 37: Specific fault in that system

Frequently asked questions

Can I keep driving with code U0037?

It depends on which control module has dropped out. If it affects the engine, brakes, or steering, do not continue your trip: call for roadside assistance.

What causes code U0037?

The most common causes are: wiring or node fault on bus B; gateway module routing CAN messages incorrectly; cAN terminating resistor (120 Ω) drifted out of spec.

Related codes

• U0029Vehicle Communication Bus A Performance
• U0028Vehicle Communication Bus A
• U0046Vehicle Communication Bus C
• U0055Vehicle Communication Bus D
• U0064Vehicle Communication Bus E
• U0089Vehicle Communication Bus G
• U009BVehicle Communication Bus I
• U009DVehicle Communication Bus J

Sources

• github.com: dtc database
• en.wikipedia.org: CAN bus

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.