Bad DEF quality or ?

Hey Brother. I had this happen on a Cascadia w/ISX in my shop couple of years ago. If I recall correctly it ended up being that stupid ambient temperature sensor mounted on the front bumper support. Reason it sticks in my memory is because it did not make much logical sense. I will have to check the customers work order on Monday to make sure that I did not forget anything. Getting old, memory starting to go......

 

3364/2 is caused by 4364/18 if the tank was refilled before 4364/18 became active.

 

Just give it the old taste test.

Is that yellow light in the DEF gauge only for indicating low level?

I've had problems with that before. It was on but the gauge said it was half full, but it really was empty. Was wiring harness problems for the DEF tank sensors, it wan an intermittent problem.

 

I get that enough that I carry on. Yes my DEF full and low Def light illuminates. Last time it stayed on for 200 miles. Likely common with freightliners if not the whole industry. Forced regen does not eliminate the idiot light.

 

When NOx outlet detects the SCR conversion isn't proper it will trigger a DEF quality fault code assuming the fluid quality is bad. Most times it ends up being a NOx outlet sensor drifting or the SCR module on it's way out or even the metering unit not spraying enough DEF into the SCR module because of a faulty PLU for example.

 

The ISX do have the ammonia sensor on the SCR. The newer ones do not and require a jumper harness to avoid a fault code and ECM calibration. You might of had a bad ground on the ambient air temperature sensor? If I'm not mistaken or at least on the CM871 ISX aftertreatment temperature sensors share the same ground circuit with the coolant level sensor and the ambient air temperature sensor.

 

You are 100% correct on that one. They do all share the same ground.