U0240: Lost Communication With Entrapment Control Module B

What it means

A control module has stopped receiving expected messages from entrapment control module B. 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 B monitors or controls an entrapment-protection function assigned to it by the vehicle design. U0240 is set when another module stops receiving expected network messages from module B, which is distinct from module A.

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 check for other communication codes that may indicate a shared network or supply fault.
2. Identify from vehicle information which entrapment-protection function is assigned to module B, then check its status without putting anyone near a potential pinch point.
3. Inspect module B’s connector and accessible network wiring for looseness, corrosion, water intrusion, or damage.
4. Check module B’s power and ground against the manufacturer’s wiring diagram and test procedure.
5. Test the network wiring to module B for opens or shorts following the manufacturer’s procedure.
6. If power, ground, and network wiring pass, follow the vehicle-specific procedure to confirm whether module B has failed.

Common fixes

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

Can I keep driving?

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