Few CEL codes questions
 

These are pertaining to my 01 3.0 Montero Sport.


First code is
P0154
Oxygen Sensor Circuit No Activity Detected (Bank 2, Sensor 1)


Which of the Four O2 sensors is this one referring to?
EDIT: After searching, which I should have done first I see that this is the drivers side front O2 sensor.

Second code is
P0161
Oxygen O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)

Which of the Four O2 sensors is this one referring to?
EDIT: If Sensor 1 is the front O2 sensor I would assume this one is the drivers side rear O2 sensor.

I also see I may just need to take it to the dealership and have them reflash it, and then go from there. Is that something that is still recommended?

Third code is
P0401

Insufficient EGR Flow

Is there any troubleshooting I could do before just replacing the O2 sensors? and Where would you start wit the third one, the insufficient EGR Flow?

The only symptom I've been having is very occasionally it'll sputter and RPMs will drop when coming to a stop, sometimes not very often at all (maybe twice in about 4 months) when the RPMs dropped it died.

Thanks guys!

I called the dealership and they said $88 to run a diagnostic on it, and then they went on to say they doubt that will fix it, and how it could be the O2 sensor could be the cat converter.

P0154
 

I have a P0154 and P0174 as well on my '02 sport. Just started about a month ago. I haven't spent any money on it yet, but I printed out the TSB-04-13-002REV. If I'm reading it right, it sounds like the factory PCM software causes premature failure of that O2 sensor. There might be chance it is covered by warranty, but the dealer that is 50 miles away wants $60 to in order to find that out. If its not covered I will probably replace the sensor myself with a Denso sensor.

reflash rarely works. sensors will have to be changed along with the reflash. thats the fix. p0401 EGR insufficent flow is common. caused from using cheap gas, which cloggs up the EGR ports on the intake. sure fire fix is this. remove the intake, strip it down of all electrical parts and throttle body and take it to your local machine shop and have them soak it in the HOT vat overnite. be sure to blow out ALL the ports when you get it back BEFORE reassembly. works every time!