09180-03800 TIMER ASSY, AUTOMA Denso Cross

DEF Recommendations for SCR Aftertreatment Systems
For use in Cat engines, DEF must meet all the requirements defined by the "ISO 22241-1" standard.The caps of DEF tanks are typically blue as recommended by the "ISO 22241-4" Standard. Fill DEF only in clearly marked DEF tanks that have the blue cap.Caterpillar recommends the use of DEF available through the Cat parts ordering system for use in Cat engines equipped with SCR systems. Refer to Table 1 for part number information:
Table 1
Cat Part Number
(32.5% Urea) Container Size
350-8733 2.5 gal bottle
350-8734 1000-L tote In North America, commercial DEF that is API approved and meets all the requirements defined in "ISO 22241-1" may be used in Cat engines that are equipped with SCR systems.Outside of North America, commercial DEF that meets all requirements defined in "ISO 22241-1" may be used in Cat engines that are equipped with SCR systems.The supplier should provide documentation to prove that the DEF is compliant with the requirements of "ISO 22241-1".
Cat does not warrant the quality or performance of non-Cat fluids.
Do not use agriculture grade urea solutions. Do not use any fluids that do not meet "ISO 22241-1" Requirements in SCR emissions reduction systems. Use of these fluids can result in numerous problems including damage to SCR equipment and a reduction in NOx conversion efficiency.
DEF is a solution of solid urea that is dissolved in deionized water to produce a final concentration of 32.5% urea. Most SCR systems are designed to operate only on DEF concentration of 32.5 percent. DEF solution of 32.5% urea has the lowest attainable freeze point of −11.5° C (11.3° F). DEF concentrations that are higher or lower than 32.5% have higher freeze points. DEF dosing systems and "ISO 22241-1" specifications are designed for a solution that is approximately 32.5%.Cat offers refractometers that can be used to measure DEF concentration. Refer to Table 2 for the part numbers. Follow the instructions provided with the instruments.
Table 2
Cat DEF Refractometers
Refractometer Part Numbers 360-0774 Digital display, easy to use, and multifunctional
(DEF, coolant, battery fluid, and more)
431-7087 Analog, specific to DEF, and requires a multi-step test procedure DEF Guidelines
DEF solution is typically colorless and clear. Changes to color or clarity are indicators of quality issues. Quality of DEF can degrade when stored and handled inappropriately or if DEF is not protected from contamination. Details are provided below.If quality issues are suspected, testing of DEF should focus on urea percentage, alkalinity as NH3 and biuret content. DEF that does not pass all these tests or that is no longer clear should not be used.Note: Caterpillar strongly recommends that customers purchase the pre-mixed DEF urea solution from a reputable supplier. The DEF must satisfy all the specifications of quality given in this chapter of this Special Publication. Urea solutions that are not made of urea and water of the appropriate quality and cleanliness may damage the SCR system. Poor or questionable quality DEF can lead to additional repair and maintenance costs to the customer. Cat warranties do not cover failures