U0004 Code - High Speed CAN Communication Bus (+) Low
Quick Answer
A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Diagnosis of this Diagnostic Trouble Code (DTC) is accomplished via the vehicle symptom(s), Check for more codes, Faulty Control Module. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- U0004 indicates High Speed CAN Communication Bus (+) Low.
- Common causes
- Common causes include Diagnosis of this Diagnostic Trouble Code (DTC) is accomplished via the vehicle symptom(s), Check for more codes, Faulty Control Module.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code U0004 Description
What are the Possible Causes of the DTC U0004?
- Diagnosis of this Diagnostic Trouble Code (DTC) is accomplished via the vehicle symptom(s)
- Check for more codes
- Faulty Control Module
- Control Module harness is open or shorted
- Control Module circuit poor electrical connection
How to Fix the DTC U0004?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the U0004 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the U0004 code?
Need more information on how to fix the U0004 code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the U0004 code diagnosed by a professional: Find a repair shop in your area
Information for Specific Makes
- U0004 Ford — High Speed CAN Communication Bus (+) Low
- U0004 Lincoln — High Speed CAN Communication Bus (+) Low
- U0004 Mercury — High Speed CAN Communication Bus (+) Low
Frequently Asked Questions about U0004 Code
1. What are the common symptoms of OBDII code U0004?
- Common symptoms include issues with the vehicle's communication systems, such as intermittent or complete loss of communication with various modules.
2. What can cause the OBDII code U0004 to appear?
- The code U0004 typically indicates a fault in the High Speed CAN Communication Bus (+) Low circuit, which can be caused by wiring issues, a faulty CAN bus module, or a poor connection.
3. How can I diagnose the OBDII code U0004?
- Diagnosing the code U0004 involves checking the wiring harness for damage, inspecting the connectors for corrosion or loose connections, and using a diagnostic scan tool to test the communication between modules.
4. What are the possible repair options for OBDII code U0004?
- Repair options for code U0004 may include repairing or replacing damaged wiring, cleaning or replacing connectors, resetting fault codes, or replacing the faulty CAN bus module.
5. Can I drive my vehicle with the OBDII code U0004 present?
- It is not recommended to drive the vehicle with the code U0004 present, as it can lead to communication issues between critical modules and potentially affect the vehicle's performance and safety systems.
6. How serious is the OBDII code U0004?
- The code U0004 is considered a serious issue as it affects the communication bus, which can impact the functionality of various vehicle systems and may lead to further electrical problems if left unresolved.
7. Is it possible to clear the OBDII code U0004 without fixing the underlying issue?
- Clearing the code U0004 without addressing the root cause may temporarily remove the warning light, but the problem will likely resurface, potentially causing more severe issues over time.
8. Can a DIY enthusiast fix the OBDII code U0004 at home?
- Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to address simple causes of the code U0004, such as checking and repairing damaged wiring or connectors.
9. How much does it cost to repair the OBDII code U0004 at a professional auto repair shop?
- The cost of repairing the code U0004 at a professional auto repair shop can vary depending on the extent of the issue, the labor rates, and the cost of any necessary parts. It's advisable to request a diagnostic and repair estimate from a trusted mechanic.
10. Are there any preventive measures to avoid OBDII code U0004 in the future?
- To prevent the recurrence of code U0004, it's essential to regularly inspect the wiring harness and connectors for signs of wear or damage, ensure proper maintenance of the vehicle's electrical system, and address any communication issues promptly.
Discuss the causes and fixes for U0004 OBDII Code
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