Q&A

 Master

front are below thw the exhaust, either on the manifold or on the pipe.

the rears are down below behind the cats.

why are you replacing all 4?? the likely hood of all them failing is nill. maybe one but not 4. what are your concerns??

Roy

 Master

Agree with mastertech. The odds of all four going at once is astronomical. If the o2 are kicking, look for the cause to be fuel air mix caused by something else or exhaust flow being obstructed.

 Master

Agree with Roy and csubak30 get the problem properly diagnosed prior to replacing parts. If it is an O2 sensor Oxygen sensors are identified by bank and sensor position. Sensor 1 is always pre catalytic converter, sensor two is always post catalytic converter. If an engine is a 4 or 6 cylinder engine the whole engine is considered bank 1, if an engine is a V6, V8, V10....., the engine bank containing cylinder number 1 (first cylinder in the firing order) is considered Bank 1, the other bank is considered Bank 2. Interpretation Oxygen sensor designation B2S1 refers to Bank 2 Sensor 1, it will be the sensor on the engine side of the catalytic converter in bank two. Check this link to determine the cylinder that contains cylinder number 1. http://www.wellsve.com/custom_searches/ds_firing.php