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Re: Check engine light
0420 is, of course, a "catalyst efficiency" fault.
The way OBD2 works is, when the diagnostics test the cat, if the signal from the rear sensor begins to mimic that of the front sensor, the diagnostics assume the cat is failing.
One problem with some inexpensive "high-flow" cats is they contain an inadequate amount of catalytic reactant. That's why they can be sold cheap. Problem is if the cat doesn't have enough reactant to work efficiently, the rear sensor signal will mimic the front sensor and the code sets.
Using HPT, you can program P0420 to not turn on the MIL, but if the cat is not working properly, you may have trouble passing a state emissions test.
I'd say that, if you didn't have problems with P0420 before you put the aftermarket cat on but you have the code now, it's unlikely the sensor is bad, however, if you follow the diagnostic info on P0420 in the FSM, you can determine is the sensor is bad prior to buying any parts.
If the problem is, in fact, a faulty cat or a bad sensor, moving the rear sensor's position in the exhaust is unlikely to change the situation.
IMO, this whole BS about "high-flow" cats is just that, BS.
I put an standard Car Sound Exhaust replacement cat on my mod'ed 01. All I did was go a half-inch larger and inlet/outlet. I gained some performance, the exhaust sounds better and the car still passes the stringent Enhanced Smog Check in California. Oh yeah...never seen a P0420 either. The cat cost me about 200 bucks on Amazon. For more info see: http://www.camarohomepage.com/project/part5.htm
0420 is, of course, a "catalyst efficiency" fault.
The way OBD2 works is, when the diagnostics test the cat, if the signal from the rear sensor begins to mimic that of the front sensor, the diagnostics assume the cat is failing.
One problem with some inexpensive "high-flow" cats is they contain an inadequate amount of catalytic reactant. That's why they can be sold cheap. Problem is if the cat doesn't have enough reactant to work efficiently, the rear sensor signal will mimic the front sensor and the code sets.
Using HPT, you can program P0420 to not turn on the MIL, but if the cat is not working properly, you may have trouble passing a state emissions test.
I'd say that, if you didn't have problems with P0420 before you put the aftermarket cat on but you have the code now, it's unlikely the sensor is bad, however, if you follow the diagnostic info on P0420 in the FSM, you can determine is the sensor is bad prior to buying any parts.
If the problem is, in fact, a faulty cat or a bad sensor, moving the rear sensor's position in the exhaust is unlikely to change the situation.
IMO, this whole BS about "high-flow" cats is just that, BS.
I put an standard Car Sound Exhaust replacement cat on my mod'ed 01. All I did was go a half-inch larger and inlet/outlet. I gained some performance, the exhaust sounds better and the car still passes the stringent Enhanced Smog Check in California. Oh yeah...never seen a P0420 either. The cat cost me about 200 bucks on Amazon. For more info see: http://www.camarohomepage.com/project/part5.htm
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