High Speed CAN Communication Bus
The U0001 code means the vehicle's onboard diagnostic system has detected: High Speed CAN Communication Bus. This is a critical severity code.
- Keep driving?
- No -- stop driving
- DIY difficulty
- hard
- Estimated cost
- $100 - $1000 (parts and labor)
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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Common Symptoms
- Check Engine Light and multiple warning lights illuminated
- Multiple systems inoperative
- Dashboard gauges not working
- Vehicle may not start
- No communication with scan tool
Probable Causes (Ranked by Likelihood)
- Open or shorted CAN bus wiring Very High
- Failed CAN bus terminating resistor High
- Water damage to CAN bus harness Moderate
- Failed module pulling down the CAN bus Moderate
Step-by-Step Diagnostic Procedure
-
Check for CAN bus activity with an oscilloscope -- normal signal shows 2.5V differential
-
Measure CAN bus resistance between CAN-H and CAN-L -- should be approximately 60 ohms
-
Disconnect modules one at a time to find a module pulling down the bus
-
Inspect CAN bus wiring for damage, especially at connectors and harness junctions
-
Check for water intrusion in module connectors along the CAN bus
Common Fixes by Vehicle
What techs usually find when diagnosing U0001 on specific vehicles — tap your vehicle for the fix and the exact part:
2007-2018 Chevrolet Silverado/GMC Sierra hard DIY
High speed CAN bus fault typically indicates a wiring problem between control modules. Start by checking the CAN bus termination resistors -- measure resistance between CAN-H and CAN-L at the OBD port (should read 60 ohms). If open circuit, a module has dropped off the bus. Common causes: rodent damage to wiring harness, corroded connector at the transmission controller, or water-damaged BCM.
Labor: 1-4 hours (diagnosis)2008-2020 Ford F-150/Explorer hard DIY
CAN bus issues on Ford vehicles are frequently caused by a corroded connector at the Gateway Module (behind the fuse panel). The gateway bridges the HS-CAN and MS-CAN networks. Check both CAN networks with a multimeter at the DLC: HS-CAN should show 60 ohms between pins 6 and 14, MS-CAN between pins 3 and 11. If one network shows open/short, isolate modules on that bus one by one.
Labor: 1-4 hours (diagnosis)2008-2020 Chrysler/Dodge/Jeep (various) hard DIY
On Chrysler CAN bus architecture, U0001 often points to the TIPM (Totally Integrated Power Module). The TIPM is the main fuse box and also a CAN bus node. Known for internal relay failures and corroded pin connectors. Inspect the TIPM connector (large gray plug underneath) for green corrosion. Aftermarket TIPM rebuild services exist and cost less than a new Mopar unit. If replacing, the TIPM must be programmed to the vehicle.
Labor: 2-4 hours (diagnosis + repair)Frequently Asked Questions
Can I drive with code U0001?
Do not drive. Lost communication codes indicate a module has stopped communicating on the vehicle network. The affected system is completely inoperative.
What causes U0001?
The most common cause is a failed module or a wiring issue in the CAN bus network. Open or shorted CAN bus wiring is the most likely cause. Power supply, ground, and connector issues should be checked before replacing any module.
Is U0001 expensive to fix?
Repair costs range from $100 - $1000 (parts and labor). Wiring repairs are on the lower end, while module replacement is on the higher end. The module may also need to be programmed after replacement.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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