bank 1 but witch sensor

[justalfe1]

hey ive been having problems latley understanding this obd2 readout code it said i have problems with bank 1 sensor 2 does that mean that Its the oxygen sensor after the cat ( i have headers so its the lower one )???

[crazyoldcougar]

i would think bank1 is the precat sensor...if you have headers and no cat then chances are the gases are not heating the sensor up enough

[Turbo Zetec 'tour]

bank 1 refers to the bank of cylinders that contains cylinder number 1. since its a zetec it only has 1 bank of cylinders. you then have sensor 1 and sensor 2. sensor 1 is always before the CAT and the computer uses it determine air/fuel ratio and modify it as necessary. sensor 2 is after the CAT and the computer determines catylist efficency from it. since you have headers you dont have a CAT for it to monitor it sees the A/F ratio constantly changing so the PCM assumes you have a faulty CAT.you can either get a custom tune and have the downstream O2 sensor turned off. you also get the added benifit of more power. you can also just install an MIL eliminator but you wont get the extra power.

[justalfe1]

I THINK the second sensor is just bad now...the mil i bogut from cc.com is in ..so im going to try to replace that and see what happends.