What U0073 means
A control module has found that the car's main data network (CAN bus A) has stopped working, so it has stopped trying to talk on it. Because many modules share this network, several warning lights usually come on at once and the brakes, transmission or gauges may act up. A short in the network wiring or one failing module dragging the network down is the usual cause.
How the engine computer detects it
A control module has detected that the communication bus is non-functional and has shut its bus interface off. Affects multiple modules at once because none can communicate; on most vehicles the dashboard lights up with several warning lamps simultaneously.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
- CAN line shorted to supply or ground Most likely
- Terminating resistor failed Possible
- One failing module pulling the bus down Possible
How to diagnose U0073
- Check battery voltage, the battery terminals and the main ground straps. Low voltage or a bad ground can knock modules off the network.
- Use a scanner that reads all modules to see which ones stored U0073 and which can't be reached. That shows which part of the network is affected.
- Think about recent work or add-ons. Remote starters, trailer wiring, stereos or dash cams spliced into the wiring can disturb the network.
- Look for water damage or corroded connectors, especially at modules in footwells, under seats or in the trunk.
- A shop measures the network wiring at the diagnostic port, then disconnects modules one at a time to find one that is pulling the network down, or traces the wiring for a short.
Vehicles that report U0073 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Toyota Camry | 2007–2018 | 6 | 105k | |
| Chevrolet Equinox | 2011–2013 | 4 | 78k | |
| Chevrolet Silverado 1500 | 2008–2014 | 3 | — | |
| Chevrolet Malibu | 2018–2023 | 3 | — |
Counts of owner complaints to the NHTSA that mention U0073 (34 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- U
- Network
- 0
- Generic (SAE) code
- 073
- Specific fault
Questions drivers ask
Can I drive with code U0073?
Don't count on it. With the network down, the engine, transmission, ABS or power steering may not work normally. If several warning lights are on or the car drives differently, stop somewhere safe and have it towed; if everything works normally, drive carefully straight to a shop.
Often reported together
Codes that owners mention in the same NHTSA complaints as U0073. They can point to a shared cause, so it's worth checking them together.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.