U0007: High Speed CAN Communication Bus (-) Low

The CAN-Low line is shorted to ground or held below its valid recessive level. The differential pair cannot transmit data and the bus is effectively dead.

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

• CAN-Low shorted to ground
• Failed transceiver on one module
• Gateway module routing CAN messages incorrectly

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. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Identify which control module is not responding and check its fuses, power supply, and grounds
4. Disconnect add-on accessories, such as alarms or trackers, and read the codes again
5. Inspect the network connectors for moisture or bent pins
6. 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 U0007 means

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

Frequently asked questions

Can I keep driving with code U0007?

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 U0007?

The most common causes are: cAN-Low shorted to ground; failed transceiver on one module; gateway module routing CAN messages incorrectly.

Sources

• 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.