Level Sensor 591-3427 535-6922 Fits for Caterpillar C4.4 C3.6 Engine D4 CS66B CS56B CS14 CS16 AP455 AP655

Level Sensor 591-3427 535-6922 – Replacement for Caterpillar C4.4 C3.6 Engine D4 CS66B CS56B CS14 CS16 AP455 AP655

Aftermarket diesel exhaust fluid (DEF) level sensor engineered for accurate fluid level monitoring and reliable emissions system performance in Caterpillar engine and equipment applications. Precision-manufactured components ensure drop-in compatibility with correct fitment.

Technical Specifications

• Part Numbers: 591-3427, 5913427, CA5913427, 535-6922, 5356922, CA5356922
• Tank Interface: 4
• Suction Fitting Diameter: 3/8 in
• Return Fitting Diameter: 5/16 in
• Coolant Inlet Fitting Diameter: 5/8 in
• Coolant Outlet Fitting Diameter: 5/8 in
• Header Height: 11.4 in
• Installation Depth: 337.41 mm (~13.28 in)
• Wire Length: 15.5 in
• Electrical Connector: Deutsch DT4 (STD), 4-pin
• Condition: New, aftermarket replacement
• Function: Monitors DEF tank fluid level and transmits data to the engine control module to maintain emissions compliance and prevent low-fluid shutdowns across Caterpillar Tier 4 engine and equipment applications

Equipment Compatibility

Note: Compatibility is provided for reference. Please verify against your part number before ordering.

Fits the Following Applications:

• Caterpillar Engine: C4.4, C3.6
• Caterpillar Tractor: D4
• Caterpillar Asphalt Paver: AP400, AP455, AP500, AP555, AP600, AP655, PE636
• Caterpillar Compactor: CP12, CP14, CP16, CP56B, CP68B, CP74B, CS12, CS13, CS14, CS16, CS17, CS19, CS56B, CS66B, CS68B, CS74B, CS76B, CS78B
• Caterpillar Motor Grader: 120 GC

Why Choose This Level Sensor

The DEF level sensor is a critical emissions system component in your Caterpillar Tier 4 engine — it continuously monitors fluid level in the DEF tank and feeds real-time data to the ECM to maintain SCR system operation and regulatory compliance. A failed or inaccurate level sensor triggers fault codes, activates warning indicators, and can result in derate conditions or equipment shutdown that halts production on active job sites. This replacement unit delivers:

• Accurate level monitoring – Engineered to meet the signal output, connector, and dimensional specifications of Caterpillar C4.4 and C3.6 DEF system requirements
• Exact-fit installation – Direct replacement with correct installation depth, fitting diameters, wire length, and Deutsch DT4 4-pin connector to match Caterpillar equipment specifications without modification
• Durable construction – Built to withstand continuous DEF exposure, thermal cycling, and the demanding duty requirements of Caterpillar paver, compactor, grader, and tractor applications
• Cost-effective solution – Aftermarket quality at a fraction of dealer pricing

Package Contents

• 1 × Level Sensor 591-3427

Essential for Caterpillar C4.4, C3.6 engine, D4 tractor, AP455, AP655 paver, CS66B, CS56B, CS14, CS16 compactor, and 120 GC motor grader DEF system maintenance and level sensor replacement. Keep your Caterpillar equipment delivering full emissions compliance and uninterrupted operation on every job.