U0001: High Speed CAN Communication Bus
Key takeaways
- U0001 means a module detected a fault on the high-speed CAN bus, the network that carries engine, transmission, ABS and steering data.
- Drive short trips only if the car starts and runs normally; a no-start, stalling or lost power steering means tow it.
- Check the battery, terminals, grounds and network connectors before any module; one bad connector can take the whole network down.
- Several manufacturer bulletins describe U0001 stored as a history code by a diagnostic tool or a module update, not a real fault.
- 19 owner complaints filed with NHTSA mention U0001, and 44 manufacturer bulletins from 9 makes name it.
What U0001 means
A computer in your car noticed that its fast data network isn’t working the way it should. Scanners call it “High Speed CAN Communication Bus.” The high-speed CAN bus is the two-wire network that carries the time-critical data between the engine, transmission, ABS and stability control, and on many cars the power steering. Chrysler, Jeep and Ram service information calls it CAN C.
U0001 is a network-level code. Instead of saying “I lost one module” (like U0100), the module that stored it is saying the network itself had errors, went quiet or showed a wiring fault. Many scanners add a suffix such as -00, -82 or -88 that narrows down the type of failure; write it down, since bulletins often refer to it.
Is it safe to drive?
Short trips only, and only if the engine starts and runs normally. When the high-speed network drops out, the transmission may hold one gear, ABS and stability control can switch off, and gauges can go dead. That’s not a car for highway speeds.
The answer becomes no if it won’t start, stalls, or you lose power steering. On cars with electric steering, the steering module lives on this network, and a stall at speed takes power assist off the brakes as well. Have it towed. A stored U0001 with no symptoms after a battery change is a different story; see below.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Weak battery or low voltage during cranking | Battery load test; code appeared after a jump, a flat battery or a cold start | $0 if it only needed a charge; $150–$350 for a battery |
| Loose or corroded battery terminals, engine or body grounds | Voltage drop test across cables and ground straps | $20–$120 |
| Wet, corroded or damaged network connector or wiring | About 60 ohms between the two network pins at the diagnostic port on most cars (battery disconnected); inspect connectors and harness for water, corrosion or chafing | $100–$180 to diagnose; $100–$250 to repair |
| Scan tool, plug-in tracker or add-on device on the port | Code is history only, or stops after the device is removed | $0 |
| One failing module shorting the network | Shop unplugs modules one at a time until the network recovers | $500–$1,500 for most modules; $800–$1,800 plus programming for an engine computer |
| Module software fault | A bulletin covers your make, model and year; shop reflashes | $100–$200 |
What to check first
- Test the battery and charging system. A healthy battery rests near 12.6 volts and running voltage usually sits between about 13.5 and 14.7. Our battery keeps dying guide covers the checks.
- Clean and tighten the terminals and grounds, including engine-to-body straps.
- Remove anything plugged into the diagnostic port and anything wired into the network after the car was built.
- Read codes from every module. A basic engine-only reader can miss the picture; the list of modules that logged U0001 or lost contact points to the section of network at fault. See how to read check engine light codes.
- Clear it and drive only if the car runs normally. If it stays gone for a week, don’t chase it.
- Ask about bulletins before a module is ordered. Several bulletins say U0001 can be a leftover: Harley-Davidson traced historic ABS U0001 codes to a dealer tool left connected, and Land Rover describes it stored in the ABS module on 2013–2016 Range Rovers. Stellantis bulletins cover Ram 2500 and 3500 engine computer software updates and ask technicians to call their support line before replacing a Ram 1500 steering gear for U0001.
19 owner complaints filed with NHTSA mention U0001. The Jeep Cherokee and Chrysler Pacifica have 3 each. These are owner reports, not confirmed defects.
What it costs
The cheap outcome is a battery charge, a tightened terminal or an unplugged device, $0–$120. The common outcome is a new battery or a connector or wiring repair, $100–$350 plus diagnosis. The expensive outcome is a replacement module, $500–$1,500 for most and $800–$1,800 plus programming for an engine computer, and it should come last. Paying $100–$180 to test the network first is cheaper than one wrong module.
Related codes
U0001 often appears with U0002 (high-speed CAN bus performance), U0073 (a module went bus off), and lost-communication codes such as U0100, U0101 and U0121. Many at once points at shared power, ground or wiring, not several failed modules.
What owners report to NHTSA
19 complaints filed with NHTSA mention U0001, 19 of them since 2015, across 14 different models. The component owners most often filed it under: electrical system.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| JEEP CHEROKEE | 3 | 2015, 2017 |
| CHRYSLER PACIFICA | 3 | 2017, 2018 |
Manufacturer service bulletins that name U0001
44 technical service bulletins and manufacturer communications filed with NHTSA mention U0001, from 9 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- VOLVO VOLVO TRUCK, bulletin 10207596: Volvo Chassis - Diagnostic Trouble Code ( DTC ) U0001 - 88 After Using Bendix ACOM Version 6.14
- RAM 1500 (2023, 2024), bulletin 10242715: EPS Steering Gear Prior to replacing EPS gear for Can C Bus Diagnostic Trouble Codes (DTCs), U0001 & U0002, please contact FCA Redacted Content. Please have the following info available: VIN, vehicle complaint, diagnosti…
- JEEP COMPASS (2022, 2023), bulletin 10229758: Vehicle Does Not Respond. wiTech Has Limited Or No Communication With The Vehicle. U0001-00 For CAN C Bus
- MACK CXU614 (2010, 2011, 2012, 2013), bulletin 10208571: Aftertreatment Control Module ( ACM ) Diagnostic Trouble Codes ( DTC ) U0001-88 and U0010-88 Lighting The Malfunction Indicator Lamp ( MIL ); Possible Derate Warning US10 And Newer Chassis
- RAM 2500 (2016), bulletin 10188824: Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the Engine Control Module/Powertrain Control Module (ECM/PCM) with the latest available software. The customers may experience a Malfunc…
- RAM 3500 (2016), bulletin 10222970: Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further inves…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
What is the high-speed CAN bus?
It's the fast two-wire data network that links the computers that need to share information quickly: engine, transmission, ABS and stability control, and on many cars power steering. Chrysler, Jeep and Ram call it CAN C. Slower networks handle things like the radio, locks and climate control.
Can a bad battery cause U0001?
Yes. Low voltage during cranking or after a battery has gone flat can make modules drop off the network and log U0001 along with other communication codes. Test the battery and charging system before anything else.
Can I clear U0001 and keep driving?
If the car starts and drives normally, clear it once and watch. If it doesn't return after a week, it was probably a voltage dip or a tool plugged into the diagnostic port. If it comes back, or comes with warning lights, stalling or no-start, get the network tested.
Does U0001 mean I need a new computer?
Rarely as a first step. The code says the network had a problem, not which part caused it. Wiring, connectors, grounds and low voltage are far more common. A module is replaced only after it's shown to be the one pulling the network down.