TUBE 5294665 - Caterpillar

SCR System Inspection
SCR System
Ensure that area around SCR system is clear of flammable materials.
Inspect access panels.
Inspect injector.
Inspect bulkhead fittings.
Ensure that urea and air lines are connected.
Inspect sensors.
Inspect wiring harness.Dosing Control Cabinet
Ensure that filter screens are in place.
Ensure that drains are closed.
Ensure that all lines are connected.
Check for leaking fluids. Ensure all fluids that have leaked are cleaned up and properly disposed of.
Check the A/C power supply.
Check D/C power supply.Partial Load Operation and Hydrocarbon Release Procedures
Extended operation at low load may cause increased oil consumption and allow unburned fuel to pass through the exhaust system. Unburned fuel and oil passing through the SCR system can result in aftertreatment system damage if allowed to accumulate. The accumulation of fuel and oil on the catalyst is referred to as Hydrocarbon (HC) Loading. To maintain engine efficiency, performance, and avoid possible SCR aftertreatment damage, the engine should be shut down rather than allowed to idle for an extended length of time.The SCR control will continuously estimate HC catalyst levels and a warning will be triggered if the HC loading reaches a preset threshold.If a warning occurs, a manually initiated mitigation procedure as prescribed below is required to prevent catalyst damage. This procedure slowly increases exhaust temperature and then catalyst temperature releases the HC from the catalyst. During this procedure, the aftertreatment system control will continue to estimate the HC catalyst loading.If the aftertreatment control reports excessive HC loading, execution of the mitigation procedure is recommended as soon as possible. Do not allow exhaust temperatures to exceed outlined in the procedure. Failure to follow these recommendations may result in damage to the Aftertreatment system.
Table 1
Application Maximum
Idle
Duration Engine
Load
Hrs <%
C32, 3500, C175 10 10 It is recommended that if HC release procedure does need to be executed, it is more efficient to perform the procedure prior to shutting down and allowing the system to cool. Starting from a cold system is less effective and will burn more fuel.The following fault codes are related to the hydrocarbon accumulation and release process:SPN 2434-1 Engine Exhaust Manifold #1 Temperature #1: Low-Most Severe (3)
When SPN 2434-1 is active, this code requires the operator to follow the HC Release Procedure.Level 3 - The Level 3 Code indicates that the operator must follow an HC Release Procedure to remove the high HC accumulated on the catalyst and protect the catalyst from damage. If an emergency occurs and the release procedure cannot be followed before exceeding the CEM inlet temperatures outlined in the procedure, the catalyst may be damaged.SPN 2434-18 Engine Exhaust Manifold #1 Temperature #1: Low-Moderate Severity (2)
If SPN 2434-18 is active, continued idling or low load operation (typically 20% load or less) may result in catalyst HC loading levels requiring operator action to perform the recommended hydrocarbon release procedure.Level 2 - The Level 2 Code is annunciated to provide the operator or technician a warning to change operation to prevent high HC accumulation. Engine HC Release Procedure must be ran to avoid a Level 3 diagnostic.Thermal Management/Mitigation
HC Release Procedure
If your