P0420 Catalyst Efficiency

curve457 · Aug 18th, 2006, 08:04 PM

ok i have my cousins car that came up with DTC p0420 Cat Effiecency. Also a O2 sensor high voltage code. now when i looked at the real time data with the scanner i noticed that the first o2 was fine and it fluctuated from .1-.9 volts= ok

then i looked at the second o2 and was frozen at .290 volts. now i was like, ok new o2 sensor(btw it is and 2002 Spec V) changed it, got rid of dtcs, and then i looked back at the data and noticed it was still the same. i was lyke wtf. i looked at the plug to make sure everything was fine, ok. next thing i pulled out was the wiring diagram to see which wire was the signal to the ecm. the blu/red was the bat voltage to both sensors. blk was ground on the manifold. pnk/wht heater gounrd i think, from ecm, and wht was the signal to the computer. nowi probed the wht wire, and it was the same as the scanner said, and i wasnt bouncing when i had my friend step on the gas. i shut the car off becuase i was burning my hands and looked at the scanner and it stil read .290 volts and the first o2 sensor was reading .000 volts. the i unplugeed it and probed the computer side of the plug and it still read .290. now i am totally confused and i wanted to know if anyone has any idea what is going on. the cat is not bad because prior to finding out what the dtc was, i was driving just lyke my 05 spec v. no power loss at all.

PLEASE HELP ME.. the dealer is not an option