Got code read today

[a70rose]

On the 9th I posted about my engine light, I was told to get the codes read & post them so someone could help me with it.
I found an Auto Zone to read the code for free like suggested, my is showing code 172 the the Zone guy says o2 sensor.Can anyone tell me anymore than that?
Is that what 172 is & how imp is this?
Thanks
a70rose@bellsouth.net

 

[97BlackX5.0]

okay well i dont know exactly what your code entails but if he told u it was an oxygen sensor then those are located in your exhaust pipes.... im not sure what engine you have so i cant tell you exactly where they are but you should have one before the caylytic converter.... looks like a muffler and one after the muffler..... if i am wrong on this someone correct me.... what an oxygen sensor does is detects the amount of oxygen and different gasses leaving the engine and adjusts fuel/air ratios according to get every ounce of power/economy out of the fuel. I know that with newer explorers (i have a 97 V8 with 4 oxygen sensors) that the code usually tells you which one it is. Its as simple as buying the sensor and replacing it... (Remember the diagnostic code points towards a problem.... doensnt neccessarily mean its the sensor but usually it is) If you can change a spark plug on your truck you can change this sensor.... they will run about 45dollars if you buy it at a parts store.... If you need to wait a little on replacing this you can because the computer stops adaptively adjusting the fuel air ratios and goes into a (limp mode) which is not the best for economy and power..... hope this helps and if im wrong about any of this i would like to be informed as this is what i learned when i went through this....

 

[Cali' Explorer]

Ok a70rose. I looked up your code in my handy dandy Haynes Manual. According to Sir Haynes, code 172 means "Heated Oxygen Sensor Indicates Lean Condition, right side". What this means is your right side bank is reading lean.

Now, there are a bunch of different things that could cause this. I see you have a '92 (at least, looks like it), so I would guess you have higher mileage. I would suggest replacing the Right Side (I assume they mean Passenger Side) oxygen sensor and see if it makes your CEL go away (have the codes cleared by Autozone first). If after replacing the O2 sensor and clearing the code you are still having a problem, there are a number of things you can do.

To replace the O2 sensor requires a special socket, I've found if you have a good local mechanic, they will usually do the job for $30 - $40. It isn't a difficult job if you have the sockets, all you have to do is disconnect the sensor, pull the sensor and replace it. I do believe you need a special socket so that the socket can clear the senso wire, but other than that, its a pretty simple procedure (Spray some penetrating lube before doing this, it will make getting the old sensor out easier).

For other things, you'll need to either ask someone with an older 4.0 or get yerself a Haynes manual (they're invaluable).

 

[Glacier991]

This may be a good place to explain that simply because a sensor is telling you something, it does NOT necessarily mean that the sensor itelf is bad. That's like shooting the messeger. It MIGHT be bad, but other causes can exist too. Code 172 says that the O2 sensor is not switching across threshold voltage

(read the thread on here about computer control of engines for more info on this - link here: http://www.explorerforum.com/forums/showthread.php?t=80692)

and is staying on the "lean" indication side of the crossover voltage. Now it MIGHT be a bad O2 sensor (slow or no crossover is usually the death sign for these) but it could be a vacuum leak, for example. It is smart diagnosing to consider what other conditions can lead to the indication before you go blindly replacing things. Candidly, in this case it is more likely than no it IS the sensor, but that doesn't mean I wouldn't check for other obvious things first.

Read this thread for more information on codes and the check engine light: http://www.explorerforum.com/forums/showthread.php?t=82038&highlight=Check+Engine+Light+Myths

 

[putter]

most of the time when your ford product has a 171, or 172 code it due to something or than the O2 sensor. most of the time it is caused by faulty mass air flow sensor, some times you can remove the MAF sensor and clean it. remove the top and clean the tip of the wire. just spray a little carb cleaner and blow off with air gun carefully. you could also have low fuel pressure or vaccum leaks but start with the MAF.

 

[Positive Vibes]

You only are getting one code??

I would clean the MAF, check your vacuum lines, maybe replace some cheap stuff first (FPRC and stuff).

I pulled an O2 code, cleaned the MAF and replaced the FPRC and it cleared my codes.

As stated before the O2 sensor code doesn't mean its the sensor itself.

 

[MrShorty]

For information's sake: '92 Explorer only has one O2 sensor.
Was that 172 a KOER code or a continuous memory code (Do the guys at Autozone even know about the KOER test?) The reason I ask is that a KOER 172 is easier to diagnose. If you get a pass code for the KOER test, but have a 172 in continuous memory, then the fault is intermittent, which makes diagnosis that much more difficult. If you get a 172 for the KOER test, then the fault is more stable, which makes it easier to find. Just make sure you run the KOER test with the engine and O2 sensor warmed up, or you will get a false lean code.
[soapbox]Along these lines, I would really recommend to anyone with a 1st generation Explorer that you learn to "pull your codes" yourself. It's easy, only requires a paper clip (though you can buy a more expensive code reader if you want) and then you can do these tests yourself and know that they were done right. The prospect of clearing the continuous memory codes and driving to see if they come back becomes quite simple. Sorry for the lecture.[/soapbox]
As noted, an O2 sensor code doesn't necessarily mean the O2 sensor is at fault. Be sure to check the wiring to the O2 sensor for breaks/bad connections. Check the fuel pressure. Check for exhaust leaks upstream from the sensor. Check for vacuum leaks.

 

[97BlackX5.0]

i did not have to have the special sockets to replace my sensor .... if you can get an end wrench on it it works just as good.... thanks for the info though you guys cleared up my understanding of oxygen sensors a little bit.... man what i wouldnt give for my 97 to only have one oxygen sensor.... rather than have four of them.....