Fault code

Hi any update on how that all turned out? I just got the aame codes spn 3556, both check engine and mil light came on about 250 miles ago, after i slept thru the night, the next day check engine light was gone but MIL light stays on.

 

SPN 3556 indicates the DOC outlet temp is does not reach or goes over the expected temprature. Depending on the FAIL or FMI number. Diagnostics lead to rather a bias/bad temp sensor or an inoperative HC (hydrocarbon) Doser System.
I’ve recently diagnosed a truck with this code and it ended up being the HC doser block was plugged. We replaced it, but I would suppose a person with better luck could have blockage unplug itself and the problem disappear.. but my luck rarely falls that way....

 

I have run into this problem, it could be the dosr injector clooged up ornot functioning. 2nd i changed the block doser and fuel compensation pressure went above 70 which is good but temps across the filters didnt reach the what they should. Lastly I changed the little manifold on the fuel pump, and it solved my problem. It is held on the fuel pump with 3 bolts.

 

The “block” is the fuel regulator for the HC doser system. The regulator, the doser block(control), and the doser injector it’s self make up the system. The injector is the cheapest, followed by the regulator and the doser block is the most expensive.

Just FYI for anyone who is unable to plug in the truck and would rather load the parts cannon and see what prayers can deliver!