U02A7

Code

Generic U — Network/User

Lost Communication With Engine Sound Control 1

Brand: Generic

Type: U — Network/User

Views: UK: 53 EN: 29 RU: 20

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty or unpowered Engine Sound Control 1 module
Open, short, or high-resistance wiring/circuits on CAN/vehicle network
Poor or corroded connectors or grounds
Missing or incorrect CAN termination or bus impedance
Low battery voltage or intermittent supply to module
Failed CAN transceiver or ECU internal fault

Symptoms

Malfunction of engine sound or active acoustics features (no sound, wrong sound, or constant tone)
MIL (Malfunction Indicator Lamp) or network-related warning lights may illuminate
Stored network/communication trouble codes besides U02A7
Possible reduced or altered engine behavior if feature is integrated with powertrain control
Loss of other features that rely on messages from the same module

What to check

Use a scan tool to confirm U02A7 and read freeze frame and other logged network codes
Verify battery voltage and charging system (12.0–14.5 V) with ignition on and cranking
Inspect fuses/relays that supply the Engine Sound Control module
Visually inspect connectors and wiring at the module, gateway, and related ECUs for corrosion, pin damage, or looseness
Check for multiple modules reporting communication faults (indicates shared bus problem)
Verify CAN bus termination (typically 60 ohms total between CAN high and CAN low at rest)

Signal parameters

Bus type: CAN (ISO 11898) or manufacturer-specific network
Expected message IDs: module-specific CAN ID(s) — present at regular intervals when module awake
Message frequency: periodic heartbeat (~1–20 Hz) or event-driven messages when active
Logic levels: CAN high/CAN low differential waveform; idle voltages approx. 2.5 V each, differential 0 V
Typical bus impedance: ~60 ohms across CAN high to CAN low (two 120 ohm terminators in parallel)

Diagnostic algorithm

Retrieve all DTCs and freeze frame data with a capable scan tool; record and clear codes, then attempt to reproduce.
Verify vehicle battery voltage and charging system health; charge battery if low and recheck.
Inspect fuses/relays and power/ground at the Engine Sound Control module; verify connectors are fully seated.
With ignition ON, monitor CAN bus for module heartbeat or messages using a scan tool or CAN analyzer. Note presence/absence and message IDs.
If messages are absent, trace wiring from module to the nearest gateway/ECU; check for continuity, shorts to ground or battery, and damaged insulation.
Check connector pins for corrosion, bending, or pushed-out terminals; back-probe power, ground, and CAN+/- at the module to confirm proper voltages and nominal idle voltages (~2.5 V).
Measure differential resistance across CAN high and CAN low with power off to confirm termination (~60 ohms).
If intermittent communication is suspected, wiggle-test wiring and connectors while monitoring the bus to reproduce the fault.
If wiring and bus look good, perform module-level tests: swap with known-good similar module if available, reflash/update module software per OEM procedure, or bench-test the module off vehicle if possible.
After repairs or replacements, clear codes and road test to confirm the communication fault does not return. Document findings and any module programming performed.

Likely causes

Loose or corroded connector at Engine Sound Control 1 module
Blown fuse or relay supplying the module
Damaged CAN high or CAN low wiring between module and gateway/ECU
Failed module CAN transceiver
Missing/failed bus termination resistor
Battery/charging system low voltage or intermittent

Fault status

⚠️ Status

U02A7 indicates the vehicle network has lost communication with the Engine Sound Control 1 module. The module’s messages are missing, invalid, or the module is not responding to network requests. This can be caused by wiring, power/ground, termination, transceiver or module failure, or software/configuration issues.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours