FITMENT:
Compatible with Caterpillar diesel engines and heavy equipment equipped with SCR (AdBlue/DEF) emission systems, including:

• CAT C13 / C15 / C18 engines
• CAT C7.1 / C9.3 engines
• Excavators: 336F, 349F, 374F, 390F
• Wheel loaders: 966M, 972M, 980M, 988K
• Dozers / graders: D6T, D9T, 12M, 140M, 160M series
• Off-road trucks and mining equipment

OEM / Cross reference numbers:

• 359-9171 / 3599171 / 359-9171-02
• 5WK96725A / 5WK9 6725A
• CA3599171

This is a Caterpillar SCR NOx sensor used in exhaust aftertreatment systems to monitor nitrogen oxide levels and regulate AdBlue dosing for emissions compliance.

FUNCTION:

• Measures NOx concentration in diesel exhaust gas
• Sends data to ECM via CAN communication
• Controls SCR (DEF/AdBlue) injection strategy
• Ensures EPA Tier 4 Final / Euro emissions compliance
• Helps protect DPF and SCR catalyst efficiency

INSTALLATION POSITION:

• SCR system inlet or outlet sensor (depending on machine configuration)
• Mounted on exhaust line between DPF and SCR catalyst or after SCR system

IMPORTANT NOTE:
Caterpillar NOx sensors like 5WK96725A are part of a smart sensor system with integrated electronics, meaning:

• Probe + control module are combined
• Calibration differs by engine and emissions tier
• Incorrect matching can cause SCR faults or derate

Always confirm OEM part number or engine serial number before replacement.

FAQ:

Q1: Is this inlet or outlet sensor?
A1: It can be used as inlet or outlet depending on CAT engine configuration (C13/C15/C18 SCR systems).

Q2: What equipment uses it?
A2: CAT excavators, loaders, dozers, graders, and mining trucks with SCR Tier 4 Final systems.

Q3: What are failure symptoms?
A3: SCR warning light, engine derate, NOx sensor fault codes, DEF system errors, or reduced power.

Q4: Is 5WK96725A same as 359-9171?
A4: Yes, 5WK96725A is the Continental sensor reference used for CAT OEM 359-9171 series.

Q5: Does it require programming after installation?
A5: Some CAT machines require ECM reset or SCR calibration after replacement.