P143A 2016 GMC Sierra Code - Reductant Control System Diagnostic Signal Message Counter Incorrect

The P143A code indicates an issue with the reductant control system, specifically that the diagnostic signal message counter is incorrect, which can affect the diesel exhaust fluid (DEF) system.

Common symptoms include the check engine light turning on, possible DEF system warnings, reduced engine performance, or limited speed if the DEF system is not functioning properly.

The code can be caused by a faulty reductant control module, poor electrical connections, damaged wiring, or software-related issues in the DEF system.

Driving with this code can lead to reduced performance or limp mode over time if the DEF system malfunctions, but it typically doesn’t cause immediate major damage.

Diagnosis involves scanning for codes, inspecting the reductant control module and wiring for damage or corrosion, and verifying the functionality of the DEF system components.

It may be covered under the emissions warranty, depending on mileage and the age of the vehicle. Check with your dealer for specifics.

Repair costs vary but can range from $100 to $500, depending on whether the issue is with wiring, the reductant control module, or other components.

If you’re experienced with automotive repairs, you may be able to inspect wiring or replace a faulty module. However, professional diagnosis is recommended for accurate repairs.

Clearing the code may temporarily remove the check engine light, but the underlying issue must be fixed to prevent the code from returning.

Regular maintenance of the DEF system, inspecting electrical connections, and addressing any warning signs early can help prevent this code from recurring.