U0009
High Speed CAN Communication Bus Shorted Together
1992-1998 BMW 318i E36 1.8L I4
Critical SeverityNetworkGeneric (SAE)
Description
CAN H and CAN L wires are shorted to each other, preventing differential signaling on the bus.
Symptoms
- Complete CAN bus failure
- No communication with any module on bus
- Vehicle may not start
Common Causes
- CAN H and CAN L wires shorted together
- Connector pin damage
- Crushed wiring harness
- Rodent damage to wiring
Diagnostic Steps
- Measure resistance between CAN H and CAN L (should be ~60 ohms with termination)
- Inspect wiring for physical damage
- Check connectors for bent pins
- Disconnect modules and measure resistance at each segment
Repair Notes
Locate the short between CAN H and CAN L. Common in door jambs and under-dash wiring.
Related Codes
Other Network Codes
- U0001High Speed CAN Communication Bus
- U0002High Speed CAN Communication Bus Performance
- U0003High Speed CAN Communication Bus (+) Open
- U0004High Speed CAN Communication Bus (+) Low
- U0005High Speed CAN Communication Bus (+) High
- U0006High Speed CAN Communication Bus (-) Open
- U0007High Speed CAN Communication Bus (-) Low
- U0008High Speed CAN Communication Bus (-) High
- U0010Medium Speed CAN Communication Bus
- U0028Vehicle Communication Bus A Performance
U0009 on Other Vehicles
Common Questions
What does code U0009 mean on a 1992-1998 BMW 318i E36?
U0009 stands for "High Speed CAN Communication Bus Shorted Together". CAN H and CAN L wires are shorted to each other, preventing differential signaling on the bus.
What are the symptoms of U0009 on a BMW 318i E36?
Common symptoms of U0009 include: Complete CAN bus failure, No communication with any module on bus, Vehicle may not start.
What causes U0009 on a 1992-1998 BMW 318i E36?
Common causes of U0009 include: CAN H and CAN L wires shorted together, Connector pin damage, Crushed wiring harness, Rodent damage to wiring.