U0072: Bus E (+) Circuit Open
The U0072 code indicates that a control module has detected an open circuit in the positive line of the vehicle's 'E' communication bus. This bus is typically a high-speed CAN network or a manufacturer-specific network used for communication between modules such as the powertrain and chassis systems. Loss of continuity on the CAN High line prevents data transmission on that bus, leading to communication failures.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Open circuit in the Bus E (+) (CAN High) wiring
- Loose, corroded, or damaged connector at a module on the Bus E network
- Internal failure of the CAN transceiver in a control module
- Short to ground or battery on the Bus E (+) line causing bus protection
- Defective control module (ECU) that fails to properly terminate the bus
3. Symptoms You Will Notice
- Check Engine Light or other warning lights illuminated
- Multiple modules losing communication, causing various system malfunctions
4. Step-by-Step Diagnosis
Scan all modules for communication faults and note which modules are offline
Visually inspect the Bus E (+) wiring and connectors for damage, corrosion, or looseness
Measure resistance and voltage on the CAN High line to identify opens or shorts
Isolate the faulty module by disconnecting modules one at a time while monitoring bus activity
If necessary, replace the defective module or repair the wiring
5. Frequently Asked Questions
Is it safe to drive?▼
No, driving with this code is not recommended as it can cause unpredictable behavior in critical systems like the engine, transmission, and brakes. Have the vehicle diagnosed and repaired promptly.
How much does it cost to fix?▼
Repair costs typically range from $100 to $500, depending on whether the issue is a simple wiring repair or requires replacing a control module.