1204F - DEF System Supplement
3.3 Regulations
The certification requirement on SCR systems can vary depending on the governing regulatory
body specifically between the EU and EPA.
The regulatory requirement for the SCR system is that the control system monitors DEF level and
detects control system malfunctions. The engine control system therefore, monitors the following
key SCR system parameters and applies various warnings and inducement levels to meet these
regulatory requirements.
• Low DEF level
• Degradation of DEF
• Interruption to DEF dosing (for reasons other than the tank is empty)
• Tampering or diagnostic system failure (to prevent unplugging of the level sensor for
example)
• Frozen DEF (this will be detected as interruption to DEF dosing, as frozen fluid will stop
injecting, however it is important to differentiate that the DEF is frozen as the timings and
severity of inducements are different.)
Inducement
Due to regulatory requirements, Tier 4 Final / Stage IV engines cannot be allowed to run when the
DEF system is not functioning correctly. There can be several reasons why the DEF system might
not be working properly.
Examples include poor quality DEF, lack of DEF in the tank, diagnostics, etc. In these cases, specific
actions will be taken to notify the operator. These actions will include lamps and J1939
communication. However, it must be understood that once a defined series of communications has
taken place, the engine will be required to shut down and in some cases, restart only briefly. This
strategy will not be configurable in Perkins EST. The Tier 4 Final Electronic A&I manual provides
specific information. This information is repeated here in the Mechanical Guide simply to emphasize
the issue.
A&I manual Publication TPD 1832 – Production issue 3. Page 17 of 41
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