What it means
Intermittent dropouts or noise on input power line A. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
The module monitors its A input-power feed for interruptions or unstable readings. This code sets when the feed drops out or fluctuates unpredictably, which may interrupt the module’s operation or its messages to other modules.
Common causes
Most likely first.
- Connector loose or corroded
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
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
How to diagnose it
- Save freeze-frame data and scan all modules for matching communication or voltage faults to identify when the A-feed dropout occurred.
- Inspect the module’s A-feed connector, fuse, wiring, and ground for looseness, corrosion, chafing, or heat damage.
- With a scan tool or meter, monitor the A-feed voltage while gently moving the accessible harness and connector to look for interruptions.
- Check voltage drop across the A-feed and ground under the manufacturer's specified test conditions, since resistance can cause intermittent supply loss.
- If the power feed remains stable, use the vehicle wiring diagram to inspect gateway routing and test CAN network wiring and termination to the manufacturer's specification.
Common fixes
- Clean and secure a loose or corroded A-feed connector.
- Repair chafed or broken A-feed wiring or a poor ground.
- Replace a damaged fuse terminal or connector pin.
- Repair a confirmed gateway or CAN termination fault if the A supply is stable.
Can I keep driving?
If the module or dependent functions cut out, warning lights appear, or the vehicle loses predictable control, stop driving safely and arrange diagnosis; intermittent faults can become complete failures. If no safety-related function is affected, keep the trip short and avoid relying on functions that are dropping out.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.