Late last week My truck threw 2 codes, P0171, P1171 and had P0130 "pending". The truck also idled roughly after getting off the freeway. Quick search told me I needed to replace the front O2 sensors, no biggie.

I replaced both sensors with exact fit Bosch sensors from Autozone. About 20 miles later I got the following codes: P0174, P1174, P0150. I then went back and cleaned the connector on the drivers side (I had the Bank numbering backwards), and reduced the code to P0150.

I watched the voltage graph for both of the sensors after cleaning and noticed that Bank 1 was going up and down at a nice regular interval but Bank 2 was very sluggishly seesawing around 0.4V.

Great, I got a bad sensor I thought. My tools are at my parents house which is also next to work. So I had to drive the truck this morning. At lunch I figured I drove a few blocks down the road to get a sandwich and watch the graph. This time though, Bank 1 was at 0.1V and Bank 2 was around 0.8V, and now have both P0130 and P0150 coming up.


SO... my questions:
Is it possible that both of the O2 sensors are bad?
Could the passenger side O2 sensor that originally threw a code after replacement be causing the ECU to over compensate and throw the P0130 code?
Could I have "bad gas"?
I always put Shell Premium gas in, usually from the gas station down the street from work. It might be coincidence but the rough idle started on the drive home after getting gas from there last week. I also had the Purge Valve code come up on the drive home from getting gas there a few months ago.
If it is bad gas, would a can of seafoam and a top off (I'm at half a tank) at another station cure my woes?

Thanks

 

Bank 1 is on the Cylinder #1 side.
Bank 2 is on the Cylinder #2 side.

Sensor 1 is the front sensor before the cat.

Sensor 1 will go from .1 to .9 volts rather fast.
Both should have the same rate.

If sluggish - replace it.

Sensor 2 is behind the cat.

Sensor 2 WILL NEVER oscillate.
Sensor 2 is a constant value - nearly when it is hot.
Sensor 2 measures the effectiveness of the CAT it is behind.

Sensor 2 will not affect mixture. It only exists to throw a code that your cat efficiency is below thresholds.


Replace both sensor 1 in bank 1 and bank 2 with good Bosch and you are fine.
You may have gotten a used sensor as new at Autozone.
They just toss stuff over the counter.

 

They looked new, both had the same thread goop that wasn't smeared (if you've replaced your O2 sensor that should make sense).

I replaced both of the Pre-cat Sensors. I used part #15175. Exact fit Bosch.

So jfall, you're of the impression they both failed on me?

 

Post a picture of the new O2 sensors....

I would take them both back for replacements and then put in the replacements from Autozone.

You may have gotten a bum sensor.
Sorry.

Yeah, replace them. Easy for me to say, right????

I did replace one in my truck and it solved my problems..

You could try to just replace the sluggish one.

But, if it were me, take them both back, get new ones and put them in.
Just make sure they don't give you back the same ones.
As you smartly noted - the grease will "tell" you they were used or not.

A bosch is usually a fatter sensor - not skinny.
Hopefully these are in the black Bosch box
and not a china sensor which was re-branded to be Bosch.

 

I went ahead and rescued the boxes from the recycle bin and I still have the receipts. After work tomorrow I'm taking the new ones out and returning them. I'll take some pictures of them for posterity.

 

Smartly done.
Best of luck on that job of replacing the 2 sensors.
As such - they will come out easy.
And, the connector is fresh in your mind.
1/2 hour tops I bet.

 

I myself have had many issues with Auto zone parts not fitting my vehicles (Saab and Land Rover) and although they have good customer service, its best not to buy your Rover parts from places like Auto zone. Buy exact parts from a Rover specific source. Or buy AS RECOMMENDED by fellow Rover owners, from places like Amazon. In my opinion places like auto zone are only good for buying things like fluids or parts for cheap domestic vehicles - not ideal for buying parts for particular fuzzy European vehicles. Our Rovers are as needy as live babies..... they need the specific best of the best. Best fuel, best plugs and wires, best oil etc. That's just my opinion though. But a lot of times the computers at Auto zone will state that a specific part on the shelf will fit your vehicle, but when you go to install it you find out the hard way that it does not fit at all. Just a month ago I bought front and rear duralast gold break pads for my Saab, according to the auto zone computer they fit my car, I got them home, took my wheels and calipers off only to learn that the parts auto zone sold me did not even come close to fitting on my car! I was pissed! I should have inquired with fellow Saab owners on Saabcentral.com first to see where they buy their parts. Also happened again when I bought new high Beam bulbs from autozone..... did not fit my Saab at all!

 

The sensors I bought are exact fit for the Discovery, the part number is the same as listed on Amazon and referenced through the forum. They were in Black Bosch boxes and came with a warranty. It sucks they crapped out a day after putting them in, but these sorts of things happen.

I doubt there is a corporate conspiracy at Autozone to sell defective or incorrect parts to everyone who doesn't drive a Ford or Chevy.

 

I had the same problem about two weeks ago. After replacing mine with the same part number as you from autozone. I had them on for two weeks, and didn't have time to mess with them. After disconnecting my battery for another repair they worked fine and have for three weeks.I'm not recommending resetting your computer and I'm going to get yelled at for even saying this.but my computer was not reading the new sensors another forum member told me they had a similar experience.....I'll bet your o2 isn't bad based on what i just delt with. It was giving me a150 and a 130.

 

How long did you have the battery disconnected?