I have 4 codes on a 2004 Cadillac srx p0420,p2188,p2190,p0446 , what one do I start with???

SOURCE: 1998 toyota camry V6

P0420 indicates you have a catalyst efficiency issue; replacement of the Air-Fuel Sensor should take care of that;
The P0441, P0446 and (I assume P0440); you said 446 twice, indicates a faulty or loose fuel cap; it is not sealing properly.
Please feel free to respond to me if you have any further questions.
A FixYa rating from you regarding my assistance would be greatly appreciated.

SOURCE: Replacing front turn signal bulb on 2006 Cadillac SRX

wow i feel sorry for you because Cadillac designed this bulb to be a don't get to bulb but OK here's what you do take the bottom cover off or skid plastic panel under neath the front end theirs little plastic clips holding it on just get come dikes and don't cut them but just use it to help pull them out. after you get that off use a flash light and locate your light housing you should see two screws holding the house in i think those screws are 8mm i cant remember remove those two screws and be careful the metal from the bumper cuts you pull the light housing out and remove all the screws around the housing and open the housing up replace the bulb and make sure your contact to the bulbs clean and then reassemble the way you took apart. if you cant get it well then best bet is take it somewhere i know Cadillac charges an arm and a leg so you can go somewhere else.

SOURCE: Changing fuel filter on 2004 Cadillac SRX

If you go to the auto parts store they should have a fuel line disconnect tool that has a 5/16ths end an a 3/8ths end. The tool is shaped like an X. Before you start you need to pull the fuel pump fuse under the front of the REAR passenger side seat while the car is running and let it stall. it will release the built up pressure. This is important unless you want gas to spray every where. Then take the tool and start with the end of the filter with two lines. Place the appropriate end of the tool over the smallest inlet, push the tool in then pull the line towards the filter and then push the line away and it should disconnect. Do the same with line above. Then you can use the two appropriate size wrenches to disconnect the outlet end. reconnecting the new filter is simple just make sure your quick connect lines click in all the way and you tighten the outlet line well, I think its like 22 or 25 ft/lbs.

SOURCE: Starting disabled remove key

VEHICLE ANTI THEFT SYSTEM HAVING PROBLEMS

SOURCE: what is the firing order of 2004 V8 4.6L cadillac

firing order as follows:1 2 7 3 4 5 6 8 hope this helps 4.6 northstar