Volvo: Stalling Volvos, and what to do about pesky codes, o2 sensors, origional post

Question
Jimmy,
As I stated in my post, I have already replaced Both O2 Sensors, as well as having the injectors serviced and installing new spark plugs. Like I was trying to explain, many of the codes that come up are vague and Do Not pinpoint problems, the PO172 code only says that the system is too rich.  It does not point to the O2 Sensors, it doesnt point to anything.  There are several things that could cause a rich condition, wich is why these vague codes are so expensive to fix.  You have to keep throwing parts at it until the check engine light stays off. It is only pointing to a general area, the O2 sensor is what is telling the computer that it is too rich, that is why my second step was the fuel injectors.  The MAF could be the problem, but I already replaced the MAF last year, I would be upset if that thing only lasted a short time.  
Last time it went bad though the car was stalling, like many of the people posting here, wich is what led me to make my origional post. I wanted to give some other ideas on the stalling problem that people were experiencing.

-------------------------
Followup To
Question -
I have read many questions regarding stalling while sitting as well as while running at speed.  Never rule out the MassAirFlow Sensor.  Not one time has that sensor been mentioned.  Many times the codes thrown out are vague and rarely pinpoint the problem. I have experienced the same problem described in several posts and the MAF fixed it.

A clogged Fuel filter will cause the check engine light to come on, but will rarely stall the car at idle. It will nearly stall on the freeway when the engine is demanding more fuel.

some times minor check engine codes can be cleared by disconnecting the battery for a few minuites.  One post described a helpful mechanic shorting the battery! NEVER attempt, unless you want to kill all of your electronics!

I have experienced several problems with my 98 V70 and have learned alot in the few years that I have owned the car. Sometimes like some of the people that have posted here, chasing problems can get expensive.

Currently I am chasing a PO172 (bank 1 too rich) code, and I can get it to stay away,(60 miles is the longest it has stayed off) so far I have replaced both O2 Sensors, fuel injectors, and spark plugs.  Like I mentioned earlier, sometimes codes can be vague wich can make fixing the problem costly. As we all know parts for these cars arent cheap.

any help on the 172 code would be appreciated
I hope my post/question will be helpful to your readers.

Thank You
Mike
Answer -
Hello Mike! I would start by checking both o2 sensors.That is what the fault code is pointing to. It is possible the MAF sensor is also at fault, but the o2 sensors are the most likely cause. It is best to replace both.

Jimmy

Answer
Hey Mike! Just because you replaced the o2 sensors does not mean they are working properly. You need to know what they are doing. You also need to see what the MAF sensor is doing too. The readings you get will tell you where the fault lies. The codes are trying to tell you something. They are not as vague as you think. But also remember that the code you are dealing with is a generic code. Most OBDII code readers will give you a generic code to start your fault tracing. Volvo special tools will give you a factory specific code which is much more accurate. Expereience will tell you that there are no pesky codes. There is no magic fix for them. If you fault trace the problem correctly the codes should not come back. In some cases special tools are needed to accurately check the function of emmisions related components such as the o2 sensors, MAF sensor and fuel pressure. If you do not have the proper tools or the fault trace procedure, it is best to let an expereinced Volvo technician check it for you. Sometimes that is the most cost effective way to go.

Jimmy