General question about DEF & SCR function
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Cargo Master
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From: Des Moines
General question about DEF & SCR function
I’ve had a question that’s been nagging me for no particular reason, and since my Google skills are worse than my motor skills, I’m hoping someone more knowledgeable about these systems can provide the answer.
I’m asking this from a theory/principles of operation stand point, so it’s based on the assumption that it’s an otherwise functional system.
Without the presence of DEF, is the SCR completely inert, or will it still provide some level of NoX reduction?
In other words, if I’m watching a live data feed of the upstream and downstream NoX sensors, will the downstream sensor register any reduction in NoX levels if there’s no DEF being injected into the exhaust stream?
I service plenty of these systems but I’m still learning about them - this isn’t related to one particular diagnosis but it’s been on my mind and I can’t seem to find the answer.
Thanks.
I’m asking this from a theory/principles of operation stand point, so it’s based on the assumption that it’s an otherwise functional system.
Without the presence of DEF, is the SCR completely inert, or will it still provide some level of NoX reduction?
In other words, if I’m watching a live data feed of the upstream and downstream NoX sensors, will the downstream sensor register any reduction in NoX levels if there’s no DEF being injected into the exhaust stream?
I service plenty of these systems but I’m still learning about them - this isn’t related to one particular diagnosis but it’s been on my mind and I can’t seem to find the answer.
Thanks.
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Cargo Master
Joined: Jul 2009
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From: Des Moines
Thanks. I knew that DEF initiated the reaction but I wasn’t sure if the coating on the honeycomb structure would react with NoX on its own.
In hindsight, I realized that when any fault is detected with the system, DEF injections are suspended in order to protect the catalyst, so logic and reasoning (which often escapes me in the moment
) would’ve led me to the same conclusion.
In hindsight, I realized that when any fault is detected with the system, DEF injections are suspended in order to protect the catalyst, so logic and reasoning (which often escapes me in the moment
) would’ve led me to the same conclusion.
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