Lost CAN Communication with DC-AC Converter B
The U0289 code indicates that the vehicle's main control module (typically the PCM or a master communication module) has lost Controller Area Network (CAN) communication with the DC-AC converter control module 'B'. This converter transforms direct current (DC) from the high-voltage battery or electrical system into alternating current (AC) to power specific vehicle components. The 'B' designation means there is more than one DC-AC converter, or this is a secondary/redundant unit. Loss of communication can stem from data bus faults, interrupted power supply, or internal converter 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
- Faulty CAN bus wiring (open circuit, short to ground or battery)
- Corroded, loose, or disconnected connector at the DC-AC converter 'B' module
- Internal failure of the DC-AC converter 'B' control module
- Power supply issue (blown fuse, defective relay, voltage drop)
- Faulty CAN network termination module
- Severe electromagnetic interference affecting communication signals
- Incomplete or corrupted software update in the converter module
3. Symptoms You Will Notice
- Check Engine Light or other warning lights illuminated
- Malfunction of components powered by the DC-AC converter (e.g., auxiliary outlets, inverter loads)
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect the CAN bus wiring and connectors for damage, corrosion, or loose connections
Check power supply to the DC-AC converter module (fuses, relays, voltage)
Test CAN bus termination and signal integrity with an oscilloscope
Attempt communication with the converter module using a scan tool; if no response, suspect module failure
If wiring and power are good, replace the DC-AC converter 'B' module and reprogram if necessary
5. Frequently Asked Questions
Is it safe to drive?▼
Driving is not recommended as the loss of communication can affect critical systems powered by the converter, potentially leading to further electrical issues or safety hazards.
How much does it cost to fix?▼
Repair costs typically range from $200 to $1,200 USD, depending on the root cause (wiring repair vs. module replacement) and labor rates.