AutoCodes – Generic – U0038

U0038 Code - Vehicle Communication Bus 'B' Performance

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: U0038 indicates Vehicle Communication Bus 'B' Performance.
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.

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Code Popularity 17,653

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 29, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0038 Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U0038 - Vehicle Communication Bus 'B' Performance - AutoCodes.com — U0038 Code - Vehicle Communication Bus 'B' Performance

What does this mean?

What are the Possible Causes of the DTC U0038?

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 U0038?

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 U0038 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 U0038 code?

Need more information on how to fix the U0038 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0038 code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U0038 Code

1. What are the common symptoms of OBDII code U0038 (Vehicle Communication Bus 'B' Performance)?

- Common symptoms include communication issues between various modules in the vehicle, dashboard warning lights, erratic behavior of electronic components, and difficulty starting the vehicle.

2. What are the possible causes of OBDII code U0038?

- The code U0038 can be caused by issues such as faulty wiring, corroded connectors, damaged communication modules, a defective Body Control Module (BCM), or a problem with the Controller Area Network (CAN) bus.

3. How can I diagnose OBDII code U0038?

- Diagnosing code U0038 typically involves using a professional OBDII scanner to communicate with the vehicle's computer system, checking for other related trouble codes, and inspecting the wiring and connectors for any visible damage.

4. What are some repair tips for resolving OBDII code U0038?

- Repair tips may include checking and repairing any damaged wiring or connectors, ensuring proper communication between modules, replacing faulty components like the BCM if necessary, and performing a thorough inspection of the CAN bus system.

5. Can I drive my vehicle with OBDII code U0038?

- It is not recommended to drive your vehicle with an unresolved U0038 code, as it can lead to further electrical issues and potentially affect the overall performance and safety of the vehicle.

6. How much does it typically cost to repair OBDII code U0038?

- The cost of repairing code U0038 can vary depending on the specific cause of the issue, the extent of the repairs needed, and labor rates in your area. It's best to consult with a professional mechanic for an accurate estimate.

7. Is OBDII code U0038 a serious issue?

- While code U0038 may not directly affect the drivability of the vehicle, it is considered a serious issue as it indicates problems with the communication bus system that can lead to malfunctioning electronic components and safety concerns.

8. Can a DIY enthusiast repair OBDII code U0038 at home?

- Repairing code U0038 may require advanced diagnostic tools and expertise in dealing with automotive electronics. It is recommended to seek assistance from a qualified mechanic or technician for proper diagnosis and repair.

9. How long does it take to fix OBDII code U0038?

- The time required to fix code U0038 can vary depending on the complexity of the issue, availability of parts, and the technician's experience. Some repairs may be completed within a few hours, while others may take longer.

10. Will resetting the OBDII code U0038 make it go away permanently?

- Resetting the code may temporarily clear the dashboard warning lights, but if the underlying issue causing code U0038 is not addressed, the code is likely to reappear. It's important to diagnose and repair the root cause of the problem to prevent future occurrences.