Originally Posted by dobber
Hello i'm a new member and toyota owner.My question is I have a 97 4 runner,with a 3.4 v6 and i'm getting a code p0136 sensor circuit malf. bank 1 sensor 2,downstream heated o2 sensor circuit "low voltage". The truck doesnt seem to run any different and when i erase the codes it didnt repeat for about 3 weeks.I need to know if anyone has had this problem, and did replacing the sensor cure the problem.The two times i got the check eng light it was pretty cold and within the first 5 minutes of running.Also if i do replace it should i stick with yota sensor or are aftermarkets ok.Thanx in advanced for your help,and this a great site,you've already been a big help in my rear axle seal and bearing change.
That trouble code gives me P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
So this means the O2 sensor behind the converter is bad and needs to be replaced.
I would use an OEM Toyota sensor (get them for $80 from TOR, member on Yotatech).
...or you can get them from http://www.sparkplugs.com
(at the top menu).
A new sensor will definately stop that CEL (I had the same thing happen on mine)!