HomeTrouble CodesU0006

U0006 — High Speed Can Communication Bus Open

Generic OBD-II · all makesNetwork / communication

This code indicates a break, or open circuit, in the High-Speed Controller Area Network (CAN) bus, which prevents electronic modules from communicating with each other. When the network is open, data cannot travel across the circuit, leading to a loss of function in various vehicle systems.

Symptoms

What causes it — most likely first

1. Damaged or corroded wiring

Chafed, broken, or corroded wires and connectors are the most common cause of an open CAN bus circuit.

2. Poor terminal connection

A loose, backed-out, or poorly seated terminal in a connector can create an open circuit on the bus.

3. Aftermarket equipment installation

Improperly installed aftermarket electronics, such as remote starts or alarms, can tap into or sever the CAN bus wires.

4. Internal module failure

A module connected to the bus may have an internal open circuit, severing the network connection.

5. PCM/ECM internal failure

The powertrain control module may have an internal driver failure opening the circuit, though this is extremely rare.

How it's diagnosed

  1. Perform a full vehicle scan to identify which modules can and cannot communicate to isolate the break.
  2. Visually inspect all accessible CAN bus wiring and connectors for damage, corrosion, or loose pins.
  3. Disconnect the battery and measure network resistance; infinite resistance confirms an open circuit.
  4. Split the CAN bus network at splices or module connectors, re-measuring resistance to narrow down the open section.
  5. Disconnect aftermarket accessories to rule out improper wiring interference.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Does U0006 mean my PCM/ECM needs to be replaced?

No, it almost never does. This code means there is a physical break in the network wiring or a connector. Replacing the PCM for this code is a common and costly misdiagnosis.

Can I drive my vehicle with this code?

It is not recommended. An open CAN bus can disable critical systems like the engine, transmission, ABS, or airbags, making the vehicle unpredictable and unsafe.

What does 'open' mean in this context?

In an electrical circuit, 'open' means there is a break in the path, stopping current or data from flowing. On a CAN bus, it means the digital messages cannot reach their destination.

How is the exact location of the open found?

Technicians use a divide-and-conquer method, disconnecting the bus at mid-point splices or connectors and checking resistance to see which half of the network still has continuity.