AutoCodes – Generic – U0012

U0012 Code - Medium Speed CAN Communication Bus (+) Open

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: U0012 indicates Medium Speed CAN Communication Bus (+) Open.
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 6,233

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 U0012 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 U0012 - Medium Speed CAN Communication Bus (+) Open - AutoCodes.com — U0012 Code - Medium Speed CAN Communication Bus (+) Open

What does this mean?

What are the Possible Causes of the DTC U0012?

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 U0012?

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 U0012 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 U0012 code?

Need more information on how to fix the U0012 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0012 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 U0012 Code

1. What are the common symptoms of OBDII code U0012 (Medium Speed CAN Communication Bus (+) Open)?

- Common symptoms include issues with the vehicle's transmission, cruise control, and other control modules.

2. What can cause the Medium Speed CAN Communication Bus (+) Open error code U0012?

- The code U0012 is typically caused by a break or open circuit in the medium speed CAN bus communication network.

3. How can I diagnose the U0012 code related to the Medium Speed CAN Communication Bus (+) Open?

- Diagnosis involves checking the wiring and connections in the medium speed CAN bus network for any breaks or damage.

4. Can a faulty control module trigger the U0012 code for the Medium Speed CAN Communication Bus (+) Open?

- Yes, a faulty control module connected to the medium speed CAN bus network can sometimes trigger the U0012 error code.

5. What are some repair tips for resolving the U0012 code indicating a Medium Speed CAN Communication Bus (+) Open issue?

- Repair tips include inspecting the wiring harness for damage, checking for loose or corroded connections, and repairing any faults found.

6. Is it safe to continue driving my vehicle with the U0012 code (Medium Speed CAN Communication Bus (+) Open) present?

- It is not recommended to drive the vehicle with the U0012 code active, as it can affect the proper functioning of various vehicle systems.

7. Can a simple reset of the vehicle's computer system clear the U0012 code for the Medium Speed CAN Communication Bus (+) Open?

- A simple reset may temporarily clear the code, but if the underlying issue causing the U0012 code is not addressed, it is likely to reappear.

8. How important is it to address the U0012 code indicating a Medium Speed CAN Communication Bus (+) Open problem promptly?

- It is important to address the U0012 code promptly, as it can lead to malfunctions in critical vehicle systems and potentially compromise safety.

9. Are there any common mistakes to avoid when trying to fix the U0012 code related to the Medium Speed CAN Communication Bus (+) Open?

- Common mistakes to avoid include overlooking simple wiring issues, ignoring other related error codes, and not properly testing the repairs made.

10. Can extreme weather conditions or environmental factors contribute to triggering the U0012 code for the Medium Speed CAN Communication Bus (+) Open?

- Yes, extreme weather conditions or environmental factors can sometimes lead to issues in the medium speed CAN bus network, triggering the U0012 code.