U0239: Lost Communication With Entrapment Control Module A

What it means

A control module has stopped receiving expected messages from entrapment control module A. The code identifies the communication loss; the affected entrapment-protection function depends on the vehicle.

At a glance

• Usually lights the warning light of the system that lost communication

How it works

Entrapment control module A monitors or controls an entrapment-protection function identified by the vehicle’s design. U0239 is set when another module stops receiving the expected network messages from that specific module.

Common causes

Most likely first.

1. Loss of power or ground to the module
2. Open, shorted, or damaged network wiring or connector
3. Failed module

Symptoms

• An entrapment-protection function may be unavailable
• A communication fault or warning may appear depending on the vehicle

How to diagnose it

1. Use a scan tool to record freeze-frame data and identify other communication codes that may point to a shared network or supply problem.
2. Determine from vehicle information which entrapment-protection function is assigned to module A, then check its warning messages and operation without placing anyone in a potential pinch point.
3. Inspect module A’s connector and accessible network wiring for looseness, corrosion, water intrusion, or physical damage.
4. Check module A’s power and ground using the manufacturer’s wiring diagram and test procedure.
5. Test the network wiring to module A for opens or shorts according to the manufacturer’s procedure.
6. If power, ground, and network wiring are sound, follow the vehicle-specific procedure to confirm whether module A has failed.

Common fixes

• Reconnect or repair a loose or corroded connector at entrapment control module A.
• Repair damaged network wiring to module A.
• Restore the module’s power or ground connection.
• Replace module A if circuit testing confirms an internal failure.

Can I keep driving?

Treat the entrapment-protection function assigned to module A as unavailable until the fault is repaired. Keep people clear of the affected moving part and do not rely on its obstruction protection.