Finally replaced all 4 O2 sensors w/ generics for $160.

[ohioboxster]

Jim,
I used his cars information when I punched it into mt DTC look up software.

[MNBoxster]

Originally Posted by ohioboxster

Jim,
I used his cars information when I punched it into mt DTC look up software.

Hi,

OK, my misunderstanding. But, your code description is still in keeping with bad O² sensors. If the signal from the sensor is non-existent, then a code speaking directly to the sensor will be thrown.

But, if the sensor is sending signals which are outside what the DME has been programmed to expect, it gets confused. It doesn't fault the O² sensor because it is getting a signal from it. But, it can't find any Maps to use which correspond to the signal values from the sensor, so it will code that the DME (Mfr. AF Metering) cannot function properly because that's all it knows, it doesn't know the O² is bad since it is getting an actual signal from it. An O² sensor can fail outright or it can fail progressively, sending signal values (voltages) which the DME has not been programmed to identify or interpret.

In this specific case, it could actually be one bad O² sensor, or any/all of them, which is one reason you want to change them all at the same time. They're not like lightbulbs, where you simply replace the burnt out one. Instead, they are all linked as a part of a system. Unfortunately for the wallet, this system is only as good as it's weakest link. But that doesn't mean the the remaining sensors are operating properly. Zirconia sensors work by exposing a certain surface area to Oxygen in the exhaust stream. Over 30k mi., this surface area is reduced as carbon and other contaminates condense from the exhaust stream and onto the Zirconia surface, meaning that Oxygen is now denied to that surface area, and the voltage(s) which the sensors produce decline with time as well. It is the value of these voltages which the DME uses in determining the optimal AF metering for the conditions the sensors are telling it are present.

These kind of codes are the ones which require that you put on your detective's hat to figure out what it is exactly which is causing the AF Metering to function improperly. A bad MAF can also throw similar codes as well in addition to throwing a bad MAF code. Hope this helps...

Happy Motoring!... Jim'99

[xclusivecar]

Everyone should listen to Jim on this one...I've been there done that! Once one goes they will all start setting codes and if you replace them one at a time you'll spend more time in the dealership than any of us would like to. Luckily my extended warranty covered them...but only as they expired...so I ended up dropping my car off at the dealership once a week for a month! PITA!!

[ohioboxster]

Well, for the record I dont believe anyone disagreed with Jim. We know hes a knowlegable guy.

[socratic]

I've been reading this thread with interest.
I'm at 47,500 mi on my non-S 2001, purchased about 1.5 years ago when it was at about 30 to 35,000. I can say that my car runs as fine as I remembered it at the time, but then again, there might have been a gradual deterioation since then.

My question is how do I know they need replacing? There are no cel lights yet and the car is feeling fine. As per MNBoxster, I should be way over the 30,000 mi sensor life limit.

Also, how good are the discounted ones? The Speedy/PartsTrain guys are selling them at approx $35 each. The OxygenSensors.com guys are at $114 and even then are considerably cheaper than Porsche. Is this case an exception to the rule of you-get-what-you-pay-for?

[KevinH1990]

Having just experienced a Mass Air Flow sensor failure at a bad time, I'm contemplating the replacement of my O2 sensors before they have a chance to fail. (I generally like to choose the place and time of my disasters.)

I'd just go ahead an do it if it weren't for the expense of the OEM sensors. I'll keep an eye on this thread for the next few months. I hope Jim keeps us updated on how well this is working.

[binaryc]

Ok, I finally got around to replacing all 4 sensors and I keep getting the following codes (I reset it twice and they come back within 5 miles):

• P0131: Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Signal Wire Short Circuit to Ground or Incorrect
• P0137: Oxygen Sensor After Catalytic Converter (Cylinders 1 - 3) - Signal Wire Short Circuit to Ground or Incorrect
• P0151: Oxygen Sensor Ahead of Catalytic Converter (Cylinders 4 - 6) - Signal Wire Short Circuit to Ground or Incorrect
• P0157: Oxygen Sensor After Catalytic Converter (Cylinders 4 - 6) - Signal Wire Short Circuit to Ground or Incorrect
• P1115: Oxygen Sensor Heating 1 After Catalytic Converter - Above Upper Limit
• P1119: Oxygen Sensor Heating 2 Ahead of Catalytic Converter - Below Lower Limit

I followed the instructions exactly and all the colors matched up fine. Anyone else have issues?