@Mechaniker
“That’s the secondary sensor. The primary sensor screws into the exhaust manifold, forward of the heat shield.”
You are mistaken
The sensor being pointed at is upstream of the cat, which makes it B1S1
If you look closely, there is a second sensor, further down, downstream of the cat. That is B1S2.
The second sensor is the one which is monitoring the cat efficiency
@Mechaniker I was more annoyed than offended 
When you’re talking about spending the kind of money this thing costs, it’s a good idea to make sure it’s actually broken. That same code can be sent due to a broken wire. It would suck to spend all that money on a new sensor, only to discover that you’re still getting the code because the old one was fine, but disconnected. It doesn’t take much to stick your hand down there and wiggle the wire to see if it pops loose. Better yet, it’s easy to stick a multimeter down there and see if there’s continuity on the wires. OP should do that before he spends hundreds of dollars on something he may or may not need.
Hi everyone,
I got the O2 sensor socket tool, but I can’t get the thing to budge at all. It is solid.
I drowned it in WD40, but no help. See photos below.
In the mean time it started showing code P0135 in addition to the P0134.
Thank you
That’s not a socket, it’s a “crowfoot”…You need a 6-point deep-well 1/2" drive socket and an impact wrench or breaker bar to turn it with…By the looks of the rust, don’t be surprised if the mounting port twists out, leaving a big hole in your exhaust system…
P0134: Heated Oxygen Sensor Circuit No Activity Detected (Sensor 1).
This tells you that the O2 Sensor's output does not cross 0.5 Volts after the Engine has warmed up (operating temperature above 169° F [76° C]).
This most always indicates that the O2 Sensor has completely worn out and is dead.
With the help of the Oxygen Sensor test in this article, you'll be able to confirm if the O2 Sensor has gone on to the ‘big gig in the sky’.
P0135: Heated Oxygen Sensor Heater Circuit (Sensor 1).
This tells you that the PCM has detected the heater inside the O2 Sensor has gone BAD.
99.9% of the time, this indicates that you need a new Oxygen Sensor (because its internal heater has fried).Carefully apply some heat with a torch, and you might get that sensor out
By the way, that is absolutely the correct tool to remove the sensor
If the threads strip out, don’t despair . . . there are special helicoil oxygen sensor thread inserts
If there is enough room I have had good luck using a 14 or 16" pipe wrench with a piece of pipe on the handle for leverage if needed.
That crows foot might be a great tool to install the NEW sensor, but its 3/8 drive does not have enough leverage to break that puppy loose…Cut the wires and use a deep 1/2" drive socket and breaker bar…If you have access to an acetylene torch, a brief period of incandescent heat should take the fight out of it…
I agree with @db4690 about using heat. Even Mapp gas with a simple Bernzomatic torch tip has worked for me with frozen O2 sensors.
My vote would be to cut the wires off of the old one and do as Caddyman said; deep socket in a 1/2" drive with a breakover and prayer.
Also, WD-40 does not work that well on things like this. You would be better off using PB-Blaster and allowing it to soak overnight.
" In the spring of 2008, true MAPP gas production ended in North America when production was discontinued at the only remaining plant making it. Current products labeled “MAPP” are in fact MAPP substitutes. These versions are stabilized liquefied petroleum gas (LPG) with high levels of propylene."
Once upon a time Mapp gas produced a considerably hotter flame than Propane…But the product sold today is only marginally better than Propane but it costs 4 or 5 times as much…
Thanks @Caddyman. Good info - I didn’t know that.
Is there enough clearance to use a 1/2 inch deep socket method? If so, that seems like what I’d try next, along with some heat treatment and overnight treatment with liquid-wrench or pb blaster. But maybe the crows-foot method is the only one with enough clearance.
How much torque loss do you get using a crows foot attachment I wonder? By this I mean if you used a torque wrench with a crows foot, and the torque wrench read 40 foot pounds, how much torque would actually be applied to the fastener using a crows foot? It seems like the ratio would vary crows foot to crows foot, so there’d be a conversion factor for each crows foot attachment.
“How much torque loss do you get using a crows foot attachment I wonder?”
Torque is measured from the point of force (hand) to the point of rotation (O2 sensor). If the crow’s foot is acting to lengthen the torque arm, the torque applied will be greater than the torque wrench indicates by the ratio of the total lever length to the torque wrench length.
On the other hand if you are using an extension you will get less torque due to the twisting of the extension.
Sometimes, using a hammer to tap on the sensor in every direction you can a few hundred times while spraying can help.