Code P0156 on 97 TB 4.6

Just ran a Code P0156 Sensor Circuit Malfunction (Bank 2 Sensor 2) on my TB. Trying to educate myself on this 02 sensor thing, as I understand 4 different 02 sensors are on the 4.6 engine. Please advise me which and where this 02 sensor is located on this car. Can a rookie do this job, and is a special socket involved? Any help will be appreciated.

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Brian Arnett wrote:

First you should diagnose the problem before taking off, much less purchasing, any parts.
Simply because the code says Sensor Circuit Malfunction, it does not imply that the sensor itself is the cause. It could very well be an open or shorted wire to the sensor. What sort of voltage does the computer report on that circuit, or if you don't have a full featured OBD-II tool, what do you see when you backprobe the sensor circuit wires at the ECM?
If it's a heated O2 sensor, the heater supply connection(s) may also be the culprit. It's usually a lot cheaper to fix a wiring problem external to the sensor than it is to replace the entire sensor/pigtail assembly.
If you don't have a EVTM you're pretty much playing in the dark here. I will hazard a guess that "bank 2 sensor 2" is the post-cat 02 sensor on the car's right hand side (passenger side) but don't take my word for it...
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Mark, thanks for the reply. As you can probably tell, I am no mechanic, just trying to save a trip to the dealer. My local Autozone ran the code. What you say makes very good sense, but I do not have any way of testing this 02 sensor. The Autozone readout states under hood, driver side, lower engine area, above exhaust pipe flange, mounted in exhaust manifold. Sensor located after catalytic converter, number two. Bit confusing to me, which is why I went to this forum for advise.
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Brian Arnett wrote:

A little googling shows I probably got this wrong, it appears bank 1 is on the right (passenger side, cylinders 1 2 3 4) and bank 2 is on the left (driver's side, cylinders 5 6 7 8).

If you had the documentation (wiring diagrams, theory of system operation, troubleshooting charts, etc.) and an understanding of how to make simple electrical measurements, you could spend a mere $10 on a cheap digital multimeter and make a reasonable attempt at properly diagnosing the root cause of this code.
Without the necessary information and knowledge, you are forced into attempting to do diagnosis by parts replacement, which is pretty expensive.
A buddy of mine and I easily diagnosed this exact same problem on an Audi A6, it turned out the downstream O2 sensor had gotten its wiring damaged when the exhaust system was disconnected during a clutch job. The tool we used was a laptop computer with OBD-II software that allowed us to monitor the signals coming out of the O2 sensors. From the readings we were getting it was obvious what the exact problem was, and sure enough when we got under the car you could see where the wiring had been damaged once we knew where to look.
If you could borrow a laptop, you could probably spend about $100 for an OBD-II interface and an accompanying program that would allow you to do the same thing. You probably won't get out of a dealership for less than $200 for an O2 sensor diagnosis and replacement.
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Brian Arnett wrote:

Bank 1 is always the Right hand bank on a Ford product. (Bank 1 is the bank containing the #1 spark plug). Bank 2 is the Left bank. The #1 sensors are always before (upstream) the catalytic converters. These are the ones responsible for fuel control. The #2 sensors are always after (downstream) the converters. They have no control over the fuel mixture. All they do is monitor the efficiency of the converters. Code P1156 means that there is an open or short in the O2 sensor feedback circuit (not the heater circuit)of the left upstream sensor. Inspect the connector and vehicle wiring to the sensor. Also make sure the connector is seated. If it is ok, the sensor is likely open. It's possible that there is a problem with the wiring to the PCM from the sensor, but it's very unlikely.
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OK guys will put this Thunderbird up on the ramps and see what I can come up with. Will inspect the connector and wiring, but I am assuming this will be OK. Reason being I am original owner of this car, so no one has replaced a 02 sensor. With this car being a garage queen, only 40,000 miles, pretty much like new.
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$10 on a cheap multimeter $25 on an alldatadiy.com subscription for your vehicle
Pinpoint tests... priceless. But pray you won't need a breakout box for the PCM! $200 on ebay, used.
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I cant, for some reason , come up with were TB stands for....
Offcourse , as everybody always keep asking, year, make , model ???????????/
If its a 4x4 the drivers rear O2 sensor wires sometimes get loose and are chewed by the front drive shaft causing a circuit malfunction.
Maybe something to take a look at
Just ran a Code P0156 Sensor Circuit Malfunction (Bank 2 Sensor 2) on my TB. Trying to educate myself on this 02 sensor thing, as I understand 4 different 02 sensors are on the 4.6 engine. Please advise me which and where this 02 sensor is located on this car. Can a rookie do this job, and is a special socket involved? Any help will be appreciated.
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johanb wrote:

Uhhhmm, it's a 97 Thunderbird (TB) with a 4.6L motor. I'm pretty sure it has a 4R70W (Auto) trans and is not a 4x4.
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We are into one of those areas where the PC/ED is a little hazy..... The list of possible causes is a little sparse and fails to include some conditions that could set the code.
In the grand scheme of things, one could inspect the sensor and wiring for anything obvious and then, if everything looks Kosher, replace the downstream sensor as part of the diagnostic process.... One has to assign a dollar value to their DIY diagnostic time to justify this.
In essence, this code indicates low output voltage from HO2-2.. the downstream sensor on the passengers side. What we see is that there is a lot of O2 in what's coming out of the cat.... this could mean that the Cat is bad, it could mean that there is an exhaust leak.... it could mean a lot of things. I have been the victim of customers saying "I didn't think that mattered" too many times.... Without knowing anything else abot the car, it's tough to form a reasonable reply.
Sidebar.... I chased one customer away several years ago.... His pick up had developed one nasty habit or another (can't remember quite what it was) and he refused to pay me to scan codes and data stream. His check engine light had come on about a year earlier and still ran "pretty good". That, to him, meant that this new problem had nothing to do with the check engine light.... and these people are allowed to vote.....
At any rate.... if the original poster is bent on changing this sensor.. the best tool I have so far found in a 7/8ths inch line wrench (providing you can get it in to where you need.... ). The sensor is on the drivers side after the cat.... they come out easier when things are hot....
If it was as simple as it looks, I'd be collecting welfare....
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Brian Arnett wrote:

Now that you know which sensor it is you could swap it with the other bank. You might just fix it by unplugging and plugging them in again in the process(bad connection).If you get a code for the other bank you know what it is for sure-the o2....If you get the same code you know its wiring or slight possibility the ECM. Of coarse it is always good practice to do what we call a "visual inspection" first :) Good luck.
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