What are the common causes of U049D?

A broken or chafed Glow Plug Control Module 2 wire. A corroded or damaged Glow Plug Control Module 2 connector. Corroded or damaged pins at the Glow Plug Control Module 2 connector. Bent or backed out pins at the Glow Plug Control Module 2 connector.

Pull all module codes with a scan tool. Monitor Glow Plug Control Module 2 live data for dropouts. Check the Glow Plug Control Module 2 connector for water, corrosion, or loose pins. Replace the Glow Plug Control Module 2 if the circuit and grounds test good. Clear the code and retest.

U049D

Invalid Data Received From Glow Plug Control Module 2

System: Network communication (U code)
Lamp: Check Engine Light
Category: Network Communications

What it means

U049D means Invalid Data Received From Glow Plug Control Module 2.

Where it lives

For U049D, start at the module the description names.

Check these first

A broken or chafed Glow Plug Control Module 2 wire
A corroded or damaged Glow Plug Control Module 2 connector
Corroded or damaged pins at the Glow Plug Control Module 2 connector
Bent or backed out pins at the Glow Plug Control Module 2 connector

What to do next

Pull all module codes with a scan tool
Monitor Glow Plug Control Module 2 live data for dropouts
Check the Glow Plug Control Module 2 connector for water, corrosion, or loose pins
Replace the Glow Plug Control Module 2 if the circuit and grounds test good
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.