Emission Control System (ECS)

Diesel Exhaust Fluid (DEF) Introduction

The exhaust after treatment system uses SCR (Selective Catalytic Reduction) technology which requires Diesel Exhaust Fluid (DEF) for reduction of NOx in order to enable the vehicle to comply with emission regulations. DEF, a NOx reduction agent is basically an aqueous urea solution, having a urea content of 32.5% and with the quality characteristics defined in ISO 22241-1 (AUS32) standard. DEF is a non-flammable, non-toxic, colourless and watersoluble liquid. DEF is stored in vehicle in a tank and provision is provided to refill it as per requirements. To enable SCR system to work efficiently and to ensure emission conformance, DEF meeting quality requirements of ISO 22241-1 (AUS32) standard is mandatory. Even when DEF of correct specification is filled, it’s useful life remain limited depending upon extent of exposure of storage tank/vehicle to varying environmental temperature conditions.

Refilling DEF is part of the regular maintenance service job. A tank filled to specification will normally suffice until the next maintenance Service under normal driving conditions. However as DEF consumption is highly dependent upon driving conditions/pattern, sometimes it may become necessary to get the system refilled in-between scheduled services. You need to monitor DEF Indicator Tell Tale and symbol displayed on cluster.

For failure related to SCR system, there are 3 basic tell tale which will glow based on any of the below reasons.

•Low DEF level

•Poor DEF quality

•Tampering of SCR system components

NOTE: Refer the below table in detail for SCR inducement strategy for the above DEF tell tale illumination.