Do I have a bad Cat or Sensor
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4runnernanny
New member
2006 4runner
I shut it off and when I turn it back on sounds fine, light is still on but
Does not blink. Does anyone know what it could be.
Code said coil 6 replaced it and all spark plugs.
Plz help
I have a 2006 4 runner that has the check engine light on along with VSC light/ tracking. When I start it is sounds like it's missing then engine light will blink.
I shut it off and when I turn it back on sounds fine, light is still on but
Does not blink. Does anyone know what it could be.
Code said coil 6 replaced it and all spark plugs.
Plz help
Had that code pop up on my mom's Tacoma. Tried replacing the rear O2 sensor and the code went away for a few months then returned. Replaced the front sensor in May and so far its been good since then.
How many miles on the current O2 sensors? As expensive as cats are I'd replace the O2 sensors and see if that solves the problem. In my case my mom has put over 100k on it and we've never replaced either sensor.
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Is it running fine now? Did you clear the code after you replaced the coil? If all seems to be well now try clearing the code and see if it returns.
paperchasin
New member
Regarding P0420, the best way to determine if your cat is still functioning or not is to find someone with a scan tool that can read live data. Compare the readings from the primary vs secondary O2 sensors and you should be able to determine if the cat is still good or not, and if one of your sensors is bad.
What readings am I looking for? Voltage, temps, etc.
I found an article that goes into the troubleshooting process for P0420.
The Misleading Nature of the PO42O Code - Eastern Manufacturing
paperchasin
New member
Voltage of the O2 sensors... I took this from the article posted just above this:
"..... The front O2 sensor should be switching from rich (over 600mV) to lean (under 300mV) and the rear O2 sensor, or converter monitor, should be a nice, smooth line with minimal variance in mV. When looking at the values of the O2 sensors pay particular attention to the switching rate of the sensors and be sure that neither the front nor rear sensor drops out or spikes for extended amounts of time. If either a slow switching rate or spike/drop-out happens, but the O2 then recovers and appears to be operating normally, the O2 sensor may be starting to deteriorate – or as a lot of people say, “It has become lazy” and may need to be replaced.
If you determine that the O2 sensor is lazy, remove it and check it for any type of contamination, usually by oil or antifreeze; if they are present, check the catalyst to ensure that it is not contaminated or poisoned (see Figure 3). If so, converter replacement will be necessary but not until the engine is repaired and the poisoning agent is no longer entering the exhaust, for this will lead to premature converter failure. If none of the above conditions are present and the engine is at operating temperature look at the front and rear O2 sensors. If the rear O2 sensor is mimicking the front one, the converter will most likely need to be replaced; there are only a few other easy things to look at."
GaRunner86
New member
Mine started with a po420, both sensors were bouncing back and forth and nearly the same readings, replaced the cat, and whalah! the rear o2 went to staying steady, then 2 months later my front a/f sensor got a little lazy and threw a po171, everthing checked out so i replaced the sensor, and boom all the bugs are gone.
yeah, a live data scanner is what you need. Good luck.
btw im sure you will get yelled at if you go with anything other than a Denso ( oem) sensor. Dont go "cheap", the right ones arent bad at all.
yeah, a live data scanner is what you need. Good luck.
btw im sure you will get yelled at if you go with anything other than a Denso ( oem) sensor. Dont go "cheap", the right ones arent bad at all.
zonianbrat
New member
I have a po430 code that comes in. I have a bluetooth scanner and run the torque app as well. I'm actually not too interested in fixing it yet as when the code comes it it throws out the vsc/trac stuff and I can have a little more fun in mud or snow. When I want the system on I just reset the code with my phone. Usually stays cleared for a few days. I also live in the mountains where there are no yearly smog inspections though. Just thought I would throw that out there if you can live with it because if it is cats they are not cheap.
Torque Pro has the sensors available, you'll need to check and see if they're active though. My OBD2 to Bluetooth adapter died the other day otherwise I would have checked.
For some reason all I get are readings for O2 bank 1 sensor 2 & bank 2 sensor 2. No readings for #1 sensors.
paperchasin
New member
What do these voltage readings look like if you plotted them on a graph?
Sensor 1 x 2 plots a straight line above .6 then drops straight down to below .3. Then it stair steps back up to above .6 and repeats the process.
Sensor 2 x 2 is very erratic. Small spikes and large spikes from above .6 to below .2.
paperchasin
New member
It is my understanding that Toyota calls their front O2 sensors A/F sensors. See if you can find any data/info under A/F sensors.
Very hard to make a determination, but based on this information alone, my educated guess would be that your bank 2 cat might be bad.
I'll check and see what I get tonight. My new adapter is in the mailbox at home.
