cnugget23

My '99 Mustang GT is throwing out code error code...

P0430 Catalyst System Efficiency below Limit - Bank No 2.

Triggering my Check Engine light. I have a Bassani Catted X-pipe, with SLP Loudmouth Catback and MIL eliminators installed. Have had this setup for years but the code is just now coming up. Does that mean the MIL eliminators have gone bad (Specifically the Passenger, Bank 2 side)? Or is it possible that O2 sensor or maybe even the Catalytic Converter is actually bad.

I'm suspecting its the MIL eliminator because it is last in line (wouldn't it tell computer to ignore the codes if it actually was a bad cat or bad o2)?

Just looking for some assurance because I don't want to go buy new MIL eliminators and still have this problem.

Fizzics Boy

Weird. When I had my cats on my Bassani x pipe I did not throw any codes or anything,

02 Ninja

Same thing happened to me when I had my lt's and mid pipe installed. I replaced my o2 sensors and still had the same problem. I then turned everything off with my tuner and problem was solved.

WhiteFoxGT

Could be bad Elims, but worst case scenario is a bad cat...

I'd try using someone else's if they have a set.. to see if it remedies the problem. Start replacing cheap ****, then move onto more expensive stuff (cats [:@])

cliffyk

In a normally set up system, running in closed loop mode, theoutput of the rear sensors is of a lower voltage that the front sensors and it also switches at a much lower frequency due to the fact that properly operating catalytic converters store oxygen. [/align][/align]MIL eliminators are a simple resistor/capacitor (RC) filter that reduces the voltage of the signal from the rear sensors, and introduces a bit of phase shift into the signal as well.This tricks the engine computer into thinking the converters are there and working. It should be obvious therefore that for MIL eliminators to do their thing the rear sensors must be present and working.[/align][/align]A modernPCM looks for both lower voltage and switching frequency from the rear sensors, which is why sometimes eliminators don't work--running eliminators with converters throws another factor into the equations, in fact they shouldn't be necessary if the cats are functioning. Why did you install them in the first, did you have problems> [/align][/align]I have a UPR catted X-pipe, no MIL eliminators,and no problems; have you triedremoving the eliminators?[/align][/align]

Machmax777

MILS SUCK FTW. Had to use a tuner to turn mine off

cnugget23

Ok, so sounds like its not so easy to diagnose this problem. Fizzics did you not throw codes without MILs?

Its been a while since the install, but I thought I threw codes without MILS and the catted X fitted. I then put MILs on and the code turned off.

Now, I'm getting it again, but sounds like it is more likely an O2 sensor problem (hopefully not cat) than an MIL. I guess I'll lift the car and check out the O2's. Is there an easy way to see if they work?