My 2003 Montero Limited's "Service Engine Light" lit up, the day I took it to pass emissions!!!

Anyway, I got a code P0171, Bank 1 running lean, the scan tool recomended I check the O2 sensor. '

Well, I've installed a Denso left upstream sensor, I cleaned the MAF, I changed the admittedly dirty air filter and nothing!!!!

The truck is using fuel like crazy, it sounds like a diesel and it has a slight hesitation.



Any ideas?

 

Seriously, I just had the upstream and downstream O2 sensors changed, now were into the Catalytic Converter and fuel injector, and no one has any thoughts???

 

Turns out the upstream and downstream sensors have to be changed together, also had an air leak...oh, well, it's fixed now...