Engine How I dealt with CEL code P0420!

How I dealt with CEL code P0420!

Hey guys,

As I posted earlier, my friend and I put an 03 corolla engine into my 01. The new engine works GREAT-- only problem that I had was that the check engine light was constantly coming on with code P0420-- cataylist efficiency. I did some research (and also consulted Vamp) and learned that the secondary 02 sensor heats up to a certain temperature and sends back two low voltage signals to the ECU .03V and .06V, changing every 2 seconds. When the cataylitic converter goes bad OR the 02 sensor is bad, the signal changes. I cut the BLUE signal wire from my secondary 02 sensor and used a multimeter and noted that the signal was between .01V and .08V. So either the sensor was broken or the cat was broken. BUT THEN I read a TSB that said that 03 corolla engines were falsely giving off code P0420 and thus the ECU needed a flash. Instead of testing all three of these possiblities, I ordered and installed an O2 sensor simulator www.o2simulator.com. The simulator hooks into the secondary 02 sensor setup and sends the correct signal to the ECU, making it think there is no problem with the cat (now I can make a change to the cat that won't discuss here, he he he) I haven't had a check engine light once!

This should help people who are turboing, plan on removing the cat all together, OR just getting that damed p0420.

Felix

Thanks man! Some good info here

So you got the code because of the swap, or because of some mods you did??

Anyhow, whereas bank 1 sensor 1 (pre-cat sensor) toggles rapidly between 0.1 and 0.8 or 0.9, IF the catalyst is doing it's job, the bank 1 sensor 2 (downstream sensor) should maintain a fairly level voltage and the waveform should toggle very slowly, if at all - like around 0.1-0.3 which indicates a very lean mixture. And that's what you want....ideal circumstances would be only H20 and O2 coming out the tailpipe.

Trav

Just make sure you keep enough backpressure to make it worthwhile. Otherwise you'll be as slow as all the farty Hondas and other ricers.


(Shame on you for even thinking about doing stuff like that! )