AutoCodes – Chevrolet – U0203 Chevrolet

U0203 Chevrolet Code - Lost Communication With Left Rear Door Switch Panel Control Module

Quick Answer

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Left Rear Door Switch Panel Control Module, Left Rear Door Switch Panel Control Module harness is open or shorted, Left Rear Door Switch Panel Control Module circuit poor electrical connection. 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: U0203 Chevrolet indicates Lost Communication With Left Rear Door Switch Panel Control Module.
Common causes: Common causes include Faulty Left Rear Door Switch Panel Control Module, Left Rear Door Switch Panel Control Module harness is open or shorted, Left Rear Door Switch Panel Control Module circuit poor electrical connection.
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 551

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 Apr 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0203 Chevrolet Description

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Left Rear Door Switch Panel Control Module has not been received.

OBDII Code U0203 Chevrolet - Lost Communication With Left Rear Door Switch Panel Control Module - AutoCodes.com — U0203 Chevrolet Code - Lost Communication With Left Rear Door Switch Panel Control Module

What does this mean?

What are the Possible Causes of the DTC U0203 Chevrolet?

Faulty Left Rear Door Switch Panel Control Module
Left Rear Door Switch Panel Control Module harness is open or shorted
Left Rear Door Switch Panel Control Module circuit poor electrical connection

How to Fix the DTC U0203 Chevrolet?

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 U0203 Chevrolet 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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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 U0203 Chevrolet Code

1. What does the OBDII code U0203 mean on a Chevrolet?

Code U0203 indicates the vehicle has lost communication with the Left Rear Door Switch Panel Control Module, which may affect door-related functions.

2. What are common symptoms of a U0203 code in a Chevrolet?

Symptoms may include non-functional rear left door controls, such as window or lock operation, and possible warning lights on the dashboard.

3. What causes a U0203 code in a Chevrolet?

Common causes include a faulty Left Rear Door Switch Panel Control Module, damaged wiring, loose or corroded electrical connections, or network communication issues in the CAN bus system.

4. Can a U0203 code cause other problems in my Chevrolet?

Yes, it may prevent proper operation of the left rear door controls and could indicate broader communication issues in the vehicleâ€™s network.

5. How can I diagnose the U0203 code on my Chevrolet?

Start by inspecting the wiring and connectors near the left rear door for damage or corrosion. Use a scan tool to check for additional codes and test the module's communication on the CAN bus.

6. Is it safe to drive my Chevrolet with a U0203 code?

Yes, the vehicle may still be drivable, but door functions like locks or windows might not work, which could pose a safety risk in certain situations.

7. Can a software update fix the U0203 code on a Chevrolet?

In some cases, a software update for the affected module may resolve the issue if a programming error is causing the loss of communication.

8. How do I reset the U0203 code on my Chevrolet?

Fix the underlying issue, such as repairing wiring or replacing the module, then use a scan tool to clear the code. If the problem persists, the code will return.

9. How much does it cost to repair a U0203 code on a Chevrolet?

Repair costs vary depending on the issue. Replacing a module may cost $200â€“$500, while wiring repairs could be less expensive. Diagnostic fees may also apply.

10. Can I fix the U0203 code on my Chevrolet myself?

If you have basic automotive knowledge, you can inspect wiring and connectors for damage or corrosion. However, diagnosing communication issues often requires specialized tools and expertise.