What are the common causes of U0022?

A short to ground on the low speed CAN positive wire. A partially shorted low speed CAN positive connector. A module pulling the low speed CAN positive voltage low. Water intrusion in the low speed CAN positive harness.

Read the code and check module communication status on a scan tool. Measure low speed CAN positive voltage with the key on. Test the low speed CAN positive wire for a short to ground. Inspect the low speed CAN positive connectors for moisture. Disconnect modules one at a time to find the one pulling the line low. Clear the code and retest.

U0022

Low Speed CAN Communication Bus (+) Low

System: Network communication (U code)
Lamp: Check Engine Light
Category: Network Communications

What it means

U0022 means Low Speed CAN Communication Bus (+) Low.

Check these first

A short to ground on the low speed CAN positive wire
A partially shorted low speed CAN positive connector
A module pulling the low speed CAN positive voltage low
Water intrusion in the low speed CAN positive harness

What to do next

Read the code and check module communication status on a scan tool
Measure low speed CAN positive voltage with the key on
Test the low speed CAN positive wire for a short to ground
Inspect the low speed CAN positive connectors for moisture
Disconnect modules one at a time to find the one pulling the line low
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.