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+--- Thread: 6.7 ISB QSB def doser temperature sensor reference (/showthread.php?tid=10758)
6.7 ISB QSB def doser temperature sensor reference - mikkhh - 09-21-2026
There is a 5-6 year old Swedish make truck with engine that has got red engine name all over aftertreatment parts. Def doser looks like red engine part code 5578983 . Problem is that DEF doser temperature reads 150C and the system is in complete derate. I checked the doser valve temperature sensor resistance at the plug and between pins 6 and 7 I got 27ohm. On a working truck with same doser the resistance is 4.1 kilo ohms at room temperature.
New doser is like 1300 euros + VAT, but the questions is where I could find the table for scr doser temperature sensor resistance and temperature? I have the make specific diagnostic (it has guided steps too), but they do not tell the resistance. Also the repair manual does not list it under descriptions, there is only wiring diagrams. I also tried just unplugging the doser and putting 4.1k ohms of resistance there, it did not help, got the same temperature reading with resistors and with just nothing plugged in - most likely goes to failsafe substitute reading quite fast - when cycling ignition I saw some voltage to that temperature sensor pin but it went down fast.
In this case since working truck was nearby I was able to check the resistance and tell that the doser in this case was faulty and new genuine gets ordered to replace it.
[attachment=10495]
[attachment=10496]
How the top of the cans looks like.
[attachment=10497]
Somebody has replaced temperature sensors and they have not bothered to remove the old one.