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Re: 2008 Dodge Ram 2500 Cummins 6.7 O2 sensors?
Posted to Technical Theory Forum on 7/25/2013 4 Replies

Hello there. I am a 15 year journeyman diesel technician in the heavy truck industry. Those sensors you are trying to figure out should be temp sensors. They monitor the input & output temp of the DPF ( diesel particulate filter). The engine utilizes a regeneration of the filter when exhaust restriction gets too high using a differential pressure sensor then will ask for a regen. If the vehicle is in motion at the time of a regen request it will do it passively. This is called literally a passive regen. The exhaust must be at a predestined temp to begin "dosing" the exhaust system with excess fuel causing a chemical reaction with the hydrocarbons "fuel" and the left over deposits left in the trap. The exhaust temp gets to an average temp of 700 degrees before this begins and will climb to as much as 900 or more depending on the quantity of material in the DPF. It gets it's dosing fuel by over fueling the engine slightly. I hope this helps.

Clifton Maier
Technician/Service Advisor
Meza Auto
Iowa City, Iowa, USA

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