U1804 Buick Code - Lost Communication With Inside Rearview Mirror Control Module
Quick Answer
Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Inside Rearview Mirror Control Module, Inside Rearview Mirror Control Module harness is open or shorted, Inside Rearview Mirror 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
- U1804 Buick indicates Lost Communication With Inside Rearview Mirror Control Module.
- Common causes
- Common causes include Faulty Inside Rearview Mirror Control Module, Inside Rearview Mirror Control Module harness is open or shorted, Inside Rearview Mirror 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.
Code U1804 Buick Description
What are the Possible Causes of the DTC U1804 Buick?
- Faulty Inside Rearview Mirror Control Module
- Inside Rearview Mirror Control Module harness is open or shorted
- Inside Rearview Mirror Control Module circuit poor electrical connection
How to Fix the DTC U1804 Buick?
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 U1804 Buick 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 U1804 Buick code?
Need more information on how to fix the U1804 Buick code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the U1804 Buick code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about U1804 Buick Code
1. What does the OBDII code U1804 mean on a Buick?
It means there is a loss of communication between the vehicle's control modules and the Inside Rearview Mirror Control Module.
2. What are the symptoms of code U1804 in a Buick?
Common symptoms include non-functional auto-dimming mirrors, issues with OnStar services, and possible warning lights on the dashboard.
3. What causes code U1804 to appear in a Buick?
It can be caused by a faulty Inside Rearview Mirror Control Module, damaged wiring or connectors, or issues with the CAN (Controller Area Network) communication system.
4. How can I diagnose code U1804 on my Buick?
Start by inspecting the wiring and connectors around the rearview mirror, checking for damage or loose connections. Use a scan tool to verify communication signals and test the module's functionality.
5. Can I still drive my Buick with code U1804?
Yes, but features like the auto-dimming mirror or OnStar may not function properly. It’s best to address the issue promptly to avoid further complications.
6. How do I fix code U1804 on a Buick?
Repairs may involve reconnecting loose wiring, replacing damaged connectors, or replacing the Inside Rearview Mirror Control Module if it’s defective.
7. Is code U1804 specific to Buicks with OnStar?
It is more likely to appear in Buicks equipped with OnStar since the Inside Rearview Mirror Control Module is often integrated with OnStar functionality.
8. Can a weak car battery trigger code U1804 in a Buick?
Yes, a weak or failing battery can disrupt communication between modules and potentially cause this code to appear.
9. How much does it cost to fix code U1804 on a Buick?
Costs vary but typically range from $100 to $500, depending on whether wiring repairs or module replacement is needed.
10. Will clearing the code U1804 fix the problem permanently?
No, clearing the code without addressing the root cause will only temporarily remove it, and the issue is likely to return.
Discuss the causes and fixes for U1804 Buick OBDII Code
Code U1804 Buick comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
