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AutoCodes – Generic – U0045

U0045 Code - Vehicle Communication Bus 'B' (-) Shorted To Bus 'B' (+)

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
U0045 indicates Vehicle Communication Bus 'B' (-) Shorted To Bus 'B' (+).
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 3,767
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 29, 2020
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Code U0045 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 U0045 - Vehicle Communication Bus 'B' (-) Shorted To Bus 'B' (+) - AutoCodes.com
U0045 Code - Vehicle Communication Bus 'B' (-) Shorted To Bus 'B' (+)
What does this mean?

What are the Possible Causes of the DTC U0045?

  • 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 U0045?

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 U0045 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 U0045 code?

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Need Help with the Code?

Get the U0045 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 U0045 Code

1. What does the OBDII code U0045 mean?

The U0045 code indicates that the Vehicle Communication Bus 'B' (-) is shorted to Bus 'B' (+), which disrupts communication between control modules.

2. What are the common symptoms of the U0045 code?

Symptoms may include a lit Check Engine Light, communication errors between modules, malfunctioning electronic systems, or intermittent electrical issues.

3. What causes the U0045 code to appear?

Possible causes include damaged wiring, corroded connectors, short circuits, faulty control modules, or electrical interference in the communication bus.

4. Can a faulty ECM trigger the U0045 code?

Yes, a malfunctioning Engine Control Module (ECM) can cause communication bus errors, including the U0045 code.

5. How do I diagnose the U0045 code?

Diagnose by inspecting wiring and connectors for damage or corrosion, checking for other related codes, and performing continuity tests on the communication bus.

6. Can I drive with the U0045 code active?

While you may be able to drive, it’s not recommended as the code can impact critical communication between modules, potentially leading to safety issues.

7. What tools are needed to fix the U0045 code?

You’ll need an OBDII scanner, a multimeter, and wiring diagrams specific to your vehicle to diagnose and repair the issue.

8. How do I fix the U0045 code?

Repairs might include replacing damaged wiring, cleaning or replacing corroded connectors, or replacing a faulty module if necessary.

9. Can a low battery cause the U0045 code?

Yes, a low or failing battery can disrupt the communication bus and trigger the U0045 code.

10. Is the U0045 code vehicle-specific?

No, the U0045 code is a generic OBDII code, but its exact diagnosis and repair steps may vary depending on the make and model of your vehicle.

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