Diesel oxidation catalyst
Diesel oxidation catalyst: AdBlue/DEF in the ISO 22241 class is a 32.5% by-mass high-purity urea solution in demineralized water. The page also includes a worked example and measurement sequence.
Technical frame
Diesel oxidation catalyst: AdBlue/DEF in the ISO 22241 class is a 32.5% by-mass high-purity urea solution in demineralized water. The page also includes a worked example and measurement sequence.
The technical values here expose the standard, protocol or physical relationship directly; model-specific service values are linked through the matching model/variant dossier.
The goal is not only to define the term but to let the reader calculate and interpret what the data means in a scan, scope or physical test.
Concrete technical facts
- AdBlue/DEF in the ISO 22241 class is a 32.5% by-mass high-purity urea solution in demineralized water.
- With the engine stopped, both DPF differential-pressure ports see essentially the same exhaust pressure, so near-zero sensor offset is a basic plausibility check.
- DPF pressure drop rises with exhaust mass flow; one idle value alone does not prove soot loading.
- SCR diagnosis evaluates upstream/downstream NOx, exhaust temperature, DEF dosing command and catalyst conversion in the same operating window.
- EGR command affects air mass and combustion/NOx behavior, so MAF/MAP and EGR position must be evaluated together.
- Failed regeneration should separate temperature conditions, soot model, differential pressure, combustion/fueling and inhibition reasons.
Worked example
- SCR conversion example: upstream NOx 400 ppm and downstream 80 ppm gives (400−80)/400 ×100 = 80% simple conversion, meaningful only in the proper temperature/load window.
Measurement and verification sequence
- Check DPF sensor offset with the engine stopped.
- Observe differential-pressure trend as exhaust flow rises.
- Compare EGT sensors with each other and ambient/soak conditions for plausibility.
- For SCR, log NOx in/out, DEF command and temperature together.
Fault-separation logic
- Is a valid command present and are power/ground/network healthy?
- Does feedback follow the command?
- Does an independent physical measurement confirm the output?
- Is the fault limited to a specific temperature/load/speed condition?
- Does the result remain stable when the original condition is repeated after repair?
Technical sources
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