I have a 05 4Runner, check engine light came on. Scanned it and po156 code came up. I put in a brand new from Toyota oxygen sensor(drivers side post cat.) Reset the check engine light and everything was fine for about 1200 miles.Light came on again po156. I changed the same 02 sensor and put in another brand new from Toyota 02 sensor. Then 1000 miles later the same code came up again. Has anyone else came across this problem?
02 sensor help (PO156) repeat code
- Thread starter super24w
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BlackWorksInc
New member
Did you verify that the replacement sensors were bad? The code most likely is caused by a faulty sensor but there can be other causes. If the sensor ends up being good yet the code is still tripped, you may want to check the wiring for damage.
Aren't there several O2 sensors on our cars?
BlackWorksInc
New member
That is correct, P0156 is a Bank 2, Sensor 2 problem.
As for checking them, the best way is to test them with an oscilloscope, or a scan tool. The idea is watching the voltage and the reaction time of the sensor. I realize you may not be able to do this, perhaps try swapping a known good sensor with the bad one? Also, is this the only code coming up?
As for checking them, the best way is to test them with an oscilloscope, or a scan tool. The idea is watching the voltage and the reaction time of the sensor. I realize you may not be able to do this, perhaps try swapping a known good sensor with the bad one? Also, is this the only code coming up?