Fitment

GM diesel vehicles with SCR AdBlue Euro 5 Euro 6 emission system including

• Chevrolet Silverado 2500HD 6.6L Duramax diesel (2010–2014)
• Chevrolet Silverado 3500HD 6.6L Duramax diesel
• Chevrolet Express 2500 6.6L diesel
• Chevrolet Express 3500 6.6L diesel
• GMC Sierra 2500HD 6.6L Duramax diesel
• GMC Sierra 3500HD 6.6L Duramax diesel
• GMC Savana 2500 / 3500 6.6L diesel
• Selected GM Duramax LML / LGH SCR diesel systems

OE reference
12638377
5WK96631B
12642310 (related variant reference)
12622451 (cross reference in some catalog listings)

FAQ

What is this NOx sensor used for

It measures nitrogen oxide levels in diesel exhaust gas and sends data to ECU for SCR AdBlue emission control system

Is this inlet or outlet sensor

It is commonly used as SCR Position 1 (upstream NOx sensor before SCR catalyst)

Are all 12638377 sensors interchangeable

No GM NOx sensors are ECU coded and must match exact OE number and calibration version

What system does it work with

SCR Selective Catalytic Reduction system using AdBlue injection for diesel emission compliance

What are common failure symptoms

Engine warning light SCR AdBlue fault reduced power limp mode NOx sensor communication error emission efficiency faults