It has 2 o2 sensors, one you can just see from inside the hood on the exhaust manifold/pipe the other one behind the catalytic converter under the passenger side seat ,underneath the car.
where is the bank1 o2 sensor at and how do i change it please i need your help
O2 circuit, bank 1 sensor 1, now in english you have an O2 sensor gone bad.You have 2 of them, an upstream and a downstream one. I would suspect the upstream one.
p0155 means O2 sensor, still looking for p1300 cant find it.
the exhaust, where every o2 sensor is
The upstream O2 sensor is mounted in the ehxaust manifold The downstream O2 sensor is mounted in the exhaust pipe after the catalytic converter
There are two. On the drivers side of the engine you will see a heat shield. The two O2 sensors are located at the rear of the shield. One is towards the top rear, the other is below it.
Behind the exhaust manifold.
where is the location of all o2 sensars in 99 Mazda 626
po343 is camshaft sensor 1 bad and po171 is bank1 sensor bad, in English po343 cam sensor is mounted on back of engine and hard to get to, the po171 is bank 1 o2 sensor easy to replace.
po171 means System too lean in bank 1 ,translation o2 sensor bad, probably the one before catalytic converter,but could be one after cat.
easy way is unbolt it and look thru both ends to see if it is clogged. Could have a bad catalytic converter but i would suspect O2 sensor acting up.
Most likely it is broken O2 (oxygen) sensor, but can be something else as described here: http://www.obd-codes.com/p0138 http://www.obd-codes.com/p0133