I'm really wondering, if I've spent over 500 bucks for nothing, for a new cat, after it threw the P0420 code. I've read the non-fouler in the rear sensor has very good results.....BUT.........what if the cat has been hollowed out completely though? Will it still keep it from throwing the P0420??

 

The P0420 code is thrown when the before and after cat O2 sensors are reading the same. The non fouler trick is for a hollowed out or non existent cat. It moves the post cat O2 sensor away from the exhaust so it gets a lower reading than the pre cat O2 sensor.

 

Thank you for that info. Do you or anyone know how many O2 sensors I have UPstream of the cat? I thought there was only one above, and one below. However my mech. said he thought there were TWO upstream of the cat. My eng. is the 4.3 Vortec.

 

Yes 2 upstream, one for each side. question, what if the cat has been hollowed out completely though? Will it still keep it from throwing the P0420?? Why do you ask us this? are you not telling us something? you said you replaced the cat

 

I thought I was clear..............my mech said he thought there were two sensors upstream. He's not sure. And I want to know for sure. Because if I don't know this, then how can I pass Aircare? I'd need to know if there's a second upstream ......that could be defective. And it is confusing, becuause........you say there are two upstream.............yet on my Innova 3040a scan tool, it only shows a total of two sensors (which should be the 1 up and the 1 down). There is no third sensor shown on the screen for the "O2 Sensor Test".

When my cat was replaced, mech showed me it had been hollowed out completely. I thought I had mentioned.

 

He just wanted to know if your new one had been hollowed out too.

You have 3 sensors. One on each exhaust manifold for the fuel trims. And then one after the cat to measure the efficiency of the cat. Check to make sure that downstream O2 sensor is working.
The two O2 sensors on the exhaust manifold B1S1 & B2S1 should be oscillating constantly, you should see the voltages moving between 0.200 Volts and 0.900 Volts. The rear O2 sensor's voltage should fluctuate less and stay around .5 Volts or less

 

Hi, thanks. No, the new cat is a stock......Walker ($291 CAN).

The B1S1 sometimes goes as high as .940
The B1S2 sometimes is as low as .075ish .....one of those ex. ma. sensors is new. Don't know which.

The rear of Cat sensor is new. But what is that sensor called?....B2S1? If so, that one fluctuates from .065 to .900ish.

That is what it all says now....and NOW, I'm on a road trip (to make it test-ready) because I just installed the spark plug non-fouler trick......so the rear of Cat sensor, is spaced out. And so far, after 30km........no codes! When I erased the P0420 before, it came back, in about only 6km. But..........it is possible the 1 old sensor is not working right, or even one of the new ones, possibly. My mech said to bring it in (30 min drive away) so he can test the 2 new sensors he put in. But I was hoping I could do it myself with the live data scan tool. I don't know how.

I'm depressed enough as it is..............as I just spent over $500 alone for the Cat (not including the 2 sensors)..........for NOTHING. As the non-fouler trick keeps the code from coming back, everywhere I've read. So I could have left the damn old hollowed out one in. Didn't know it was hollow though, till' he took it out.

 

Money spent wont be for nothing, should help your gas mileage

 

Thats how it goes when you take it to a mechanic. You have to pay for his time and the profit he makes off of the parts he orders.

Just for reference I paid $150 for my cat from lordco, and I paid $80 for 2 AC Delco O2 sensors off of Amazon.

If Air Care sticks the probe in your exhaust, that hollowed out cat you had will make you fail. I failed AirCare because my cat was no longer working. I installed a new cat and went back to air care the next day. The AirCare guy said those were the lowest readings he has ever seen.

 

Um.............help.

I drove it until almost test ready (only OH and EV left). And NO returning P0420. Then after all that driving, in one trip to Aldergrove, I go home to bed for work, then in one trip tonight .........it throws TWO codes, P0335 (Crankshaft Position Sensor A Circuit). Then.......P0137 (O2 Circuit Low Voltage [Bank 1, Sensor 2]). This was in hard driving in which I floored it several times.

Apparently........these two codes will make me fail Aircare?