Code P0420
#1
Code P0420
Got code P0420 today on my 2004 Mustang GT with 67k and as far as I know original 02 sensors. I have an off road x pipe with MIL'S . Long story short had a bad MIL before with bank 1 sensor 2 being lean so I made my own MIL and CEL went away.Learning more about 02 sensors than I wanted with that experience, I just wanted to know if I could check voltage at the rear 02 for atleast .50 volts will deff. tell me if the rear sensor is bad or not ? Meaning will a downstream sensor be dead or be sending low voltage if bad ?
#2
Got code P0420 today on my 2004 Mustang GT with 67k and as far as I know original 02 sensors. I have an off road x pipe with MIL'S . Long story short had a bad MIL before with bank 1 sensor 2 being lean so I made my own MIL and CEL went away.Learning more about 02 sensors than I wanted with that experience, I just wanted to know if I could check voltage at the rear 02 for atleast .50 volts will deff. tell me if the rear sensor is bad or not ? Meaning will a downstream sensor be dead or be sending low voltage if bad ?
If you disconnect the heater wires the resistance between them should be 3.3Ω or so--if not the heater is bad.
If the heater resistance is 3.3Ω or so then you can bench test the O2 sensor using the procedure described here.
A bad "MIL" (I assume you mean MIL Eliminator) on bank 1, sensor 2 (passenger side rear) would not make the engine run lean, or indicate lean operation. P0420 is also a bank 1 code so check out all possible causes for it as well as testing the sensor.
Or, just reset the code and see if it pops up again--which would be the first thing I would do...
#3
Ok , We spoke before and my lean code which the code # eludes me now. Was because one of my MIL eliminators wasn't allowing enough voltage to the computer. So I built one of your home made MIL'S and fixed that. So just learning a little about 02 sensors doing that I was just curious if I could test voltage as a tell tell sign of the sensor being bad
#5
A MIL eliminator, working or not, wired into either of the rear O2 sensors will NOT cause the engine to run lean--it cannot as the rear sensors have nothing to do with engine control--all they do is monitor catalyst efficiency.
If something I said indicated a rear sensor, or a MIL Eliminator connected to a rear sensor, could affect engine control then I was not clear in what I said, or what I said was misinterpreted...
If something I said indicated a rear sensor, or a MIL Eliminator connected to a rear sensor, could affect engine control then I was not clear in what I said, or what I said was misinterpreted...
#6
No you didn't think I'm just confusing you . My OLD code was a P2270 bank 1 sensor 2 signal stuck lean . Thats the code I found out that I had a faulty MIL eliminator. The code now is a P0420 catylist efficiency below thresehold . Thats how I found out one of my MIL eliminators was bad, cause it had to much resistance and wasn't allowing the computer to see voltage. If that makes sense
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lincolnshibuya
V6 (1994-2004) Mustangs
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12-08-2015 04:37 PM