U063E: Lost Communication With Exhaust Heat Exchanger Bypass Valve Actuator A

What it means

A control module has stopped receiving expected network messages from exhaust heat exchanger bypass valve actuator A. The effect on exhaust heat recovery depends on the vehicle's system design.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test

How it works

Exhaust heat exchanger bypass valve actuator A controls whether exhaust heat is routed through the heat exchanger for recovery. A control module expects status messages from actuator A over the vehicle network. U063E sets when those messages are lost, so exhaust heat recovery control may be unavailable and emissions related operation may be affected.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• Warning light or message related to the affected system
• Exhaust heat recovery may be affected

How to diagnose it

1. Scan all modules and review freeze-frame data for communication faults involving exhaust heat exchanger bypass valve actuator A.
2. Check live data for actuator A status and commanded position, if supported, for missing or unchanging information.
3. Inspect actuator A’s network connector and wiring for heat damage, chafing, corrosion, or loose terminals.
4. Check power and ground at the actuator or its controller against the manufacturer’s specification.
5. Test the network circuit for opens or shorts, then assess the actuator reporting module if the circuit and supplies pass.

Common fixes

• Reconnect or secure actuator A’s network connector.
• Repair heat-damaged or broken network wiring to the bypass valve actuator.
• Restore the actuator or controller’s power or ground supply.
• Replace the failed actuator reporting module after confirming the network circuit is sound.

Can I keep driving?

If the vehicle runs normally and has no temperature or exhaust warning, short, gentle trips may be possible, but the emissions related heat recovery system may not operate correctly. Avoid ignoring an exhaust or temperature warning, and have the fault repaired before an emissions inspection.