What it means
The vehicle bus reports loss of communication with engine sound control unit 1. Active sound design (interior synthetic engine sound or exterior pedestrian alert) for this channel stops.
How it works
Engine sound control unit 1 drives one channel of the vehicle's active sound system, such as cabin engine sound or an exterior pedestrian alert. U02A7 sets when the network no longer receives messages from unit 1, so that channel's sound function may stop.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
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
- Scan all modules and record freeze-frame data to check whether unit 1 lost communication with other modules or during a low-voltage event.
- Check active sound system status and live data to confirm that engine sound control unit 1, rather than unit 2, is the missing device.
- Inspect unit 1's connector and harness for loose pins, corrosion, water entry, or damage.
- Check the unit's power and ground using the manufacturer's wiring information and test conditions.
- Test the network circuit at unit 1 for opens, shorts, or poor connections using the manufacturer's procedure.
- If power, ground, and network wiring pass, confirm the unit itself has failed before replacement.
Common fixes
- Reconnect or repair a loose or corroded unit 1 connector.
- Repair damaged bus wiring to engine sound control unit 1.
- Restore unit 1's failed power or ground connection.
- Replace engine sound control unit 1 if its supplies and network circuit pass testing.
Can I keep driving?
The engine sound or pedestrian-alert channel controlled by unit 1 may be unavailable, while basic engine operation is usually unaffected. If the vehicle relies on exterior sound for pedestrian awareness, use extra caution around people until the fault is repaired.
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.