CEL came on today

I have heard a few times that even with a catted aftermarket pipe it still sets off the sensors and MIL eliminators still had to be used... I'd reccomend to check if the o2's are still connected and the wiring still intact (they could have out it too close to the pipe and it burned through the wire) if not, I'm sure it just is the fact that you changed to a better flowing pipe and some MIL eliminators may be in order...

the code is for the upstream O2 so mil eliminators won't be needed.

do you still have the code?? an exhaust leak can cause the code P0153.

you should fix the blown fuse as soon as you can. with out knowing which fuse is blown it's anyones guess.

can you simulate the rattle if you tap on the exhaust??

How did you notice a blown fuse a few days ago and now you don't know which fuse is blown?

the owners manual and/or the repair manual should have a diagram of the fuse block.

compare it to yours and see which one is missing.

unfortuatly my alldata only goes to 02 and does not show the fuse block, just the electrical diagrams.

http://www.helminc.com has owner and repair manuals. i had to use them for my stang and excursion.

The reason there is no consistency to the light coming on is because this is an O2 monitor code. There are several on board diagnostic monitors that your PCM runs,these are seperate programs kinda like the programs that run on your home computer like a virus scan or disk defrag.
The monitors on your vehicle are Catalyst Efficiency Monitor, Comprehensive Component Monitor, Evaporative Emission (EVAP) Leak Check Monitor, Exhaust Gas Recirculation (EGR) System Monitor , Fuel System Monitor, Heated Oxygen Sensor (HO2S) Monitor, Misfire Detection Monitor, PCV System Monitor.
This code you have is set when the HO2S monitor runs.
The Fuel System Monitor and Misfire Detection Monitor must also have completed successfully before the HO2S Monitor is enabled. Input is required from the ECT or CHT, IAT, MAF and CKP sensors to activate the HO2S Monitor.
Once the HO2S Monitor is enabled, the HO2S signal voltage amplitude and response frequency are checked. Excessive voltage is determined by comparing the HO2S signal voltage to a maximum calibratable threshold voltage. A fixed frequency closed loop fuel control routine is executed and the HO2S voltage amplitude and output response frequency are observed. A sample of the HO2S signal is evaluated to determine if the sensor is capable of switching or has a slow response rate. A HO2S heater circuit fault is determined by turning the heater on and off and looking for a corresponding change in the Output State Monitor (OSM) and by measuring the current going through the heater circuit.
So basically what it is doing is, when it turns on it compares the switching rate of the O2 sensor with a program in memory to see if its response rate is ok. Then it does a second test where it turns on the heater ckt in the O2 and measures the current draw and compares it to memory. The MIL is activated after a fault is detected on two consecutive drive cycles. Now for a drive cycle to complete vehicle has to go thru engine warm up, driven at certain conditions, then engine cool down. This is why there is no pattern to your CEL coming on. Now the particular code P0153 is for a slow switching response rate from the bank 2 drivers side front O2 sensor. Now the following items could cause this Contaminated or Deteriorating HO2S sensor
Exhaust leaks
Shorted /open wiring
Improper fueling/injectors clogged, dripping, etc.
MAF sensor
Inlet air leaks

Well unless you have some way to monitor data it will be tough to tell. I hate telling u to just throw parts at it but since it is only coding one side and u are sure that u don't have an exhaust leak on that side I would try replacing that O2 first.

It will turn off after three consecutive drive cycles completed without a fault. If you don't clear codes.

it's near impossible to follow but you asked.

it is the same for 96 and up shown is for 01