U0007 indicates that the high-speed CAN (Controller Area Network) communication bus has a fault on the CAN-Low circuit. This means one or more control modules are not communicating properly because the low-side signal line is shorted, open, or otherwise disrupted. It is a network-level code, not a specific component failure, so the root cause must be traced on the bus wiring and connected modules.
Chafed, corroded, pinched, or broken wiring on the CAN-Low line is the most common cause. A short to ground, short to voltage, or open circuit disrupts bus signaling for every module on that network.
A damaged, corroded, or partially seated connector at any module on the high-speed CAN bus can pull the CAN-Low line out of spec and trigger the code.
An internally failed control module on the bus can short CAN-Low to ground or voltage. This typically requires isolating modules one at a time to identify the offender.
The terminating resistors (commonly two 120-ohm resistors at opposite ends of the bus) set the bus impedance. A failed resistor or wiring to it can distort the CAN-Low signal, though it more often causes general bus errors than a specific low-side fault.
An internal failure of the CAN transceiver inside the PCM is possible but rare. It should only be considered after all wiring, connectors, and other bus modules have been conclusively ruled out.
No. In the vast majority of cases the cause is wiring, a connector, or another module on the bus. PCM internal CAN driver failure is rare and should only be suspected after everything else has been conclusively ruled out.
It depends on which modules are affected. If critical modules such as the PCM, ABS, or transmission controller lose communication, the vehicle may not start or may exhibit unsafe behavior. Have it diagnosed before driving if symptoms are severe.
Because U0007 is a network-level fault, modules that cannot communicate will each set their own loss-of-communication codes. These are usually symptoms of the underlying bus fault, not separate failures.
Poor power or ground connections can cause modules to behave erratically and may contribute to bus faults, but U0007 specifically points to the CAN-Low signal line. Grounds should be checked, but the CAN circuit itself is the primary suspect.