Hey Everyone,
New to the forum, I have a 2005 Pathfinder SE Offroad that I got about a year ago. From reading some of the posts on the forum I have had the usual problems....Rad went... tranny replaced (under warranty), fuel level sensor (replaced under warranty), rear a\c lines corroded and leaking not covered under warranty but last week I cut the lines and blocked them off, Front ac only now. So last week my "service engine soon" light came on so I pulled the code with an OBD II reader. Code was P1247 Air Fuel ratio Sensor 1. Anyone else have this problem or code come up? Is that an O2 sensor? When I come to a stop the idle seems a little off with the RPM's bouncing a bit (about 200 rpm). I love the Pathfinder (well love hate relationship) but was really hoping all the common issues were fixed!!! Thanks for your help!!!

An air/fuel ratio sensor is "sorta" like an O2 sensor, but it works a little differently and is much more precise, but looks very similar to an O2 sensor. It is typically used instead of a front oxygen sensor.

As far as your code, I think you may have gotten the # wrong, as there is no listing for a P1247 for a 2005 R51, but there is a P1274 listing, which is for the Bank #1 air/fuel ratio sensor. It's "probably" the air/ratio sensor, itself, that is setting the code, but possibilities include:
-A/F sensor
-A/F sensor heater
-fuel pressure
-fuel injector

Obviously, the only way to isolate the problem is to follow the FSM diagnostic procedure for DTC P1274.

One note you should be aware of is that after the repair has been made, the ECM self-learning must be cleared or else the code may return even if there is no problem. This was mentioned in Nissan service bulletin #NTB04-126 and would require a scantool capable of doing such.

Thanks for the quick response!! I probably did right down the wrong code...lol. I was at a buddy's that has and OBD reader. I will try and get back over there in a couple day's to confirm the code. Just have a few more questions. So is there 2 air\fuel ratio sensors and 2 O2 sensors in the R51's? Is Sensor 1 is the first sensor on the driver's side? Do you have to have a Consult II reader to resest the ECU as indicated in the TSB, Or can you reset it as described in this previous post http://www.thenissanpath.com/viewtopic. ... =reset+ecu

I can't seem to find the diagnostic procedure for code P1274 in the factory service manual am I missing something?

Any good websites Nissan Path users prefer to order parts from?

Thanks again for all your help!!

Yes, there are two, upstream (or front) air/fuel sensors and two, downstream (or rear) O2 sensors. Bank 1 is the cylinder bank that starts with #1 cylinder. For the VQ engine, it'll be the right, or passenger side, bank on a RWD vehicle like a Pathfinder or the rear bank, along the firewall, on a car like a Maxima.

I've never tried the manual reset method as I've always had a scantool that could do it, but it's worth a try!

If looking for an air/fuel sensor to purchase, I would check with Rockauto.com first and see if they have one by NTK (it's the same company as NGK) or Denso. Both of these are good brands and OEM suppliers to Asian based manufacturers. If you want a site for genuine Nissan parts, try one of these:

www.1stAAANissanParts.com

www.CourtesyParts.com

www.NissanPartsZone.com

I got my denso a/f sensors from rockauto. best price by far.

Terry I was reading a few of you previous posts regarding changing your O2 sensors in this link http://www.thenissanpath.com/viewtopic. ... c&start=15. I noticed at rock auto They called the air fuel ratio sensors O2 sensors. Did you order denso part numbers 2345060? Did you only change the front sensors? Any other issues with your gas mileage or did that fix the problem? I'm going to hook up the OBD reader tomorrow to confirm the code that's setting off the SES light.

Mileage was better for a while, but reverted back. The sensors read the exact same voltages as they did before.

I did the shotgun approach on the f/a sensors, but I'd rather not continue that approach without more symptoms or OBD codes.

Since you have the code, I'd go for it.

So it turns out I did right down the wrong code but it was P1271. Still indicated air fuel ratio sensor 1. Took a picture of the O2 sensor readings while traveling 90 kmh but can't seem to attach it using my iPhone. Here are the readings:
O2B1S1 .305
O2B1S2 .930
O2B2S1 .610
O2B2S2 .650

O2B1S1 never fluctuated at all just stayed at .305. O2B1S2 usually ran around .930 but would occasionally drop below .150

I'm going to order the front a/f sensor and change it hopefully this week. I will post results.[/img]

So I finally got around to changing the bank 1 a\f sensor. Performance has drastically improved as well as gas mileage. The last time I drove the pathy before changing the sensor my SES light came on while attempting to accelerate. Checked it again with OBD reader and pulled code P0300. All codes are cleared and hopefully problem is solved. Thanks for your help guys!!!