AutoCodes – Generic – U0033

U0033 Code - Vehicle Communication Bus 'A' (-) 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: U0033 indicates Vehicle Communication Bus 'A' (-) 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 4,337

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 U0033 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 U0033 - Vehicle Communication Bus 'A' (-) Open - AutoCodes.com — U0033 Code - Vehicle Communication Bus 'A' (-) Open

What does this mean?

What are the Possible Causes of the DTC U0033?

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 U0033?

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 U0033 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.

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Need Help with the Code?

Get the U0033 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 U0033 Code

What does OBDII code U0033 mean?

Code U0033 indicates an open circuit in the Vehicle Communication Bus 'A' (-), which can disrupt communication between modules in the vehicle.

What are the common symptoms of code U0033?

Symptoms may include warning lights on the dashboard, erratic vehicle behavior, or a loss of communication with certain control modules.

What causes the U0033 code to appear?

Common causes include damaged wiring, loose or corroded connectors, a defective control module, or issues with the CAN bus network.

Can I drive with code U0033 present?

Driving with code U0033 may be unsafe, as critical vehicle systems could be affected. Itâ€™s best to address the issue promptly.

How do I diagnose code U0033?

Start by inspecting the wiring and connectors associated with the CAN bus network for damage, corrosion, or loose connections. Use a multimeter and diagnostic tools to check for continuity.

How can I fix code U0033?

Repairs may involve replacing damaged wiring, cleaning or securing connectors, or replacing faulty control modules. Ensure all work is performed with the battery disconnected.

Is code U0033 specific to certain car brands?

No, code U0033 can appear in various makes and models, as it relates to the universal CAN bus communication system.

Will clearing the U0033 code solve the problem?

Clearing the code may temporarily erase it, but it will likely return if the underlying issue isn't resolved.

How much does it cost to repair code U0033?

Repair costs vary, depending on whether the issue is a simple wiring fix or requires module replacement. Costs typically range from $100 to several hundred dollars.

Can a faulty battery cause code U0033?

Yes, a weak or failing battery can disrupt module communication and potentially trigger U0033, so checking battery health is recommended.