Lost Communication with Entrapment Control Module A
Diagnostic trouble code U0239 indicates that the engine control module (ECM) or powertrain control module (PCM) has lost communication with the Entrapment Control Module 'A' over the CAN data bus. This module is responsible for detecting obstructions in power windows, sunroofs, or power liftgates, and typically monitors resistance during closing. Loss of communication can be caused by wiring faults, power supply issues, or internal module failure.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Open or short circuit in the CAN bus wiring
- Corroded, loose, or damaged connector at the entrapment control module
- Internal failure of the entrapment control module
- Blown fuse or poor ground to the entrapment control module
- Faulty ECM/PCM that manages bus communication
- Electromagnetic interference on the data bus
3. Symptoms You Will Notice
- Power windows, sunroof, or liftgate may not operate or close properly
- Check Engine Light or other warning lights illuminated
4. Step-by-Step Diagnosis
Scan for all stored codes and note any related U-codes
Inspect the CAN bus wiring and connectors for damage, corrosion, or looseness
Check power and ground circuits to the entrapment control module (fuses, relays, wiring)
Test the entrapment control module by attempting communication with a scan tool
If wiring and power are OK, suspect internal module failure and replace if necessary
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but power windows, sunroof, or liftgate may not function properly, and the check engine light may be on.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. Repair costs vary: a new entrapment control module ranges from $150 to $400, plus labor. Wiring repairs may be $100-$300.