the VSC lights have been on for almost a year as well as check engine light.
Time to renew registration and took in to test smog and it did not pass. Ref codes P0174, P2197 and P2238.
P2197 = oxygen sensor stuck signal stuck Lean (bank 2, sensor 1)
P0174 = system to lean (bank 2)
P2238 = oxygen sensor pumping current curcuit low (for A/F sensor) (bank 1, sensor 1)

Overall test results are:
Visual inspection: PASS
Functional check: FAIL
Emissions test: PASS

I have been researching on-line for awhile now and i cant seem to find a specific answer to what I need to do to repair? I really would rather make repairs myself, if i can figure out what i need to do exactly without having to spend $$ on oxygen sensors or a CC?

Oh and one other little tid bit of info: I just plugged my OBD2 tester into my 4runner and now the only codes that are showing are the P2197 and P2238.
the P0174 is not coming up.

Need some HELP.

i forgot to note that my vehicle runs great!

one last thing. The actual result shows "FAIL" and then indicates that:
"MIL/check engine light" "This vehicle failed the MIL/check engine light test due to a warning lamp failure."

You drove like this for a year?
Clean/check the MAF sensor, if that doesn't help take it to a pro.

Your 4runner is close or over eight years old depending on purchase date. The O2 sensors are coming up on failure / replacement time and they do tend to fail all around the same time give or take. If you want to save money try to clean the MAF sensor and O2 sensors first, also look for an exhaust leak from the manifold down, (a leak could give a lean reading if air is getting into the pipes)

How to Clean Oxygen Sensors | eHow.com

Hope this helps.

Correct. A check engine light is an auto fail because often it will throw the vehicle into a "default" or "limp" mode, whereby your all of your cars fancy emission controls are not actually operating. Depending on what is bad, your car will not be able to modify/adjust the combustion cycle to optimize the exhaust.
I have no idea how your truck is driving, but your vehicle will probably be unable to optimize settings for peak performance or exhaust output.

Also. The lean code will vary, depending on how you pull it.


Running lean for protracted periods can be very bad. Running lean means hotter, which can damage components. Your cylinder, cylinder walls, pistons and etc.
Also, the reason you fail emissions is because a lean burn typically does not work well with your standard 3 stage cat.

From Wiki:
The main drawback of lean burning is that a complex catalytic converter system is required to reduce NOx emissions. Lean burn engines do not work well with modern 3-way catalytic converter—which require a pollutant balance at the exhaust port so they can carry out oxidation and reduction reactions—so most modern engines run at or near the stoichiometric point.




If the cost of a sensor is prohibitive to you, I am not sure what to say. You can purchase a denso (regular oem for your toyota) from autozone for 70-80 bucks. I know, I just had to replace a sensor on mine 2 months ago. The denso you buy at toyota are the exact same thing, just branded "Toyota" and for that you will pay 160 bucks.
So. Honestly, it looks like your sensor is bad. Replace it. It looks like the sensor is stuck shorted. That happens. It is an electrical device shoved into your exhaust, which gets very hot.

My best bet for you, replace the sensor and move from there.