Damaged or chafed CAN+ wire on the low-speed bus, often from rodent damage, pinched harnesses, or corrosion; Poor connection at a module connector or a damaged terminal on the low-speed bus; A module on the low-speed bus internally shorting the CAN+ line to ground or to power; Corrosion or water intrusion in a connector or splice on the low-speed bus; A failed terminating resistor or fault-tolerant bus component inside a module; Aftermarket accessories improperly tapped into the low-speed bus wiring; A faulty body control module or gateway module that is not properly isolating the low-speed bus

DTC codes / U00xx · Network wiring and bus faults / U0022

U0022Low Speed CAN Communication Bus (+) Low

Q: What does code U0022 mean?

Low Speed CAN Communication Bus (+) Low. U0022 means the vehicle's low-speed Controller Area Network (CAN) data bus has a fault on the CAN+ (high-side) wire, so modules on that bus cannot communicate reliably. The computer detects an abnormal voltage or signal condition on the CAN+ line of the low-speed bus, which is typically a single-wire or fault-tolerant bus used for body and comfort modules.

U0022 means the vehicle's low-speed Controller Area Network (CAN) data bus has a fault on the CAN+ (high-side) wire, so modules on that bus cannot communicate reliably. The computer detects an abnormal voltage or signal condition on the CAN+ line of the low-speed bus, which is typically a single-wire or fault-tolerant bus used for body and comfort modules.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaNetwork wiring and bus faults

Symptoms you may notice

Multiple warning lights on the dashboard, often including the check engine light, airbag, and ABS lights
Intermittent or complete failure of body control functions such as power windows, door locks, or interior lighting
The engine may start and run normally because the low-speed bus usually does not control powertrain operation
Modules on the low-speed bus may not respond to a scan tool, or the scan tool may fail to communicate with some modules
Often no symptoms besides the warning light if the fault is intermittent or affects only non-critical modules
Erratic operation of climate control, radio, or instrument cluster features that share the low-speed bus

Common causes, most likely first

Damaged or chafed CAN+ wire on the low-speed bus, often from rodent damage, pinched harnesses, or corrosion
Poor connection at a module connector or a damaged terminal on the low-speed bus
A module on the low-speed bus internally shorting the CAN+ line to ground or to power
Corrosion or water intrusion in a connector or splice on the low-speed bus
A failed terminating resistor or fault-tolerant bus component inside a module
Aftermarket accessories improperly tapped into the low-speed bus wiring
A faulty body control module or gateway module that is not properly isolating the low-speed bus

How to diagnose and fix it

Scan all modules and record which modules are offline or setting communication codes to map the affected segment of the low-speed bus
Inspect the low-speed bus wiring and connectors for visible damage, corrosion, or loose pins, starting at the modules that are not communicating
Measure resistance and voltage on the CAN+ wire at the diagnostic connector and at each module to check for shorts to ground or power
Disconnect modules one at a time to see if the bus voltage returns to normal, isolating a module that is shorting the line
Repair or replace damaged wiring, terminals, or connectors on the CAN+ circuit and clear the codes
If a module is found to be internally shorting the bus, replace or reprogram that module as required
Verify repair by confirming all modules communicate and the code does not return after a test drive

Low-speed CAN faults hide in body harnesses

The low-speed CAN bus is often a single-wire or fault-tolerant bus, so a short on CAN+ can take down many body modules at once while the engine still runs normally.
A common mistake is replacing the body control module when the real fault is a chafed wire in a door jamb or trunk hinge that only shorts when the harness flexes.
Aftermarket alarms, remote starters, or phone chargers tapped into the wrong wire can pull the low-speed bus voltage out of range and set U0022 without any factory component being defective.
U0022 does not always mean the bus is dead; an intermittent fault can set the code only when a module wakes up or when temperature and vibration affect a marginal connection.
Some vehicles use a gateway module to isolate the low-speed bus from the high-speed bus, so a fault in the gateway can mimic a low-speed bus wiring problem.

Can I keep driving with U0022?

The vehicle is usually safe to drive because the low-speed bus mainly handles body and comfort functions, but avoid long trips until the fault is repaired. If multiple warning lights are on or the vehicle exhibits electrical oddities, have it diagnosed promptly to prevent a dead battery or loss of accessory functions.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.