INSTALLATION
MANUAL
© Scania CV AB 2018, Sweden
Periodic hydrocarbon evaporation for Stage IV/V/Tier 4f engines
01:07 Issue 17 en-GB 57
Periodic hydrocarbon evaporation for
Stage IV/V/Tier 4f engines
Periodic hydrocarbon evaporation is a function that raises the engine speed tempo-
rarily in order to prevent an excessive accumulation of hydrocarbons (HC) in the
SCR catalytic converter when exhaust gas temperatures are low.
The SCR catalytic converter accumulates hydrocarbons when the SCR system is
cold, i.e. if the exhaust gas temperature falls below 200°C. If the vehicle has been
idling for a long time and is then subjected to heavy loads, the temperature in the SCR
catalytic converter may become excessive. The hydrocarbons will not have time to
evaporate and may start burning, which can damage the SCR catalytic converter.
When the allowed amount of accumulated hydrocarbons has been reached, a warning
is output indicating that the engine must be warmed up. If the engine is idling without
load and the outdoor temperature is 20°C (68°F), the warning is output after approx.
eight hours. The time is reduced as the outdoor temperature becomes colder.
The warning is sent as a CAN message. More information about connection is avail-
able in sections ADC (Aftertreatment Desorption Control) and ADS (Aftertreatment
Desorption Status) in 03:05 CAN interface.
Periodic hydrocarbon evaporation can be selected with two different settings:
• Only warning.
• Warning and engine shutdown. Scania recommends that this setting is used for
unmanned applications.
If the engine is started again after an engine shutdown due to accumulated hydrocar-
bons, and is idling without load, the engine is switched off again after five minutes.
The measures during periodic hydrocarbon evaporation are different depending on
whether the engine is equipped with an exhaust brake or not.
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