brwilson

A note about cheap O2 sensors I found…I was having intermittent problems with a CEL for code P0139 -- Aging of Oxygen Sensor afterTWC, Bank 1. I only got it every month or so (and almost always when my wife drove the car?) but otherwise the car ran fine. No other issues. After a bit of research I thought I should replace the sensor in case it failed and somehow screwed up something expensive (i.e. cat converter). I saw that I could buy a full set of "2 Upper + 2 UnderO2 Oxygen Sensor 1, 2 For 00-01 Porsche 911 H6-3.4L SU6040 New" for less than the price of a single OEM sensor--what a deal! I paid for the sensors and they arrived in 2 days, replaced all 4 in less than an hour, and off I went, no issues, even a celebratory spirited drive through the canyons. Drove great.

All was well..until, after about 150 miles I got a CEL. This time:

• P0134, No Activity Before TWC Bank 1
• P0160 No Activity After TWC Bank 2
• P1115 (pending) Heating or O2 sensor before TWC Bank 1

No amount of clearing the codes, checking/cleaning the connections, disconnecting the battery, checking hoses, resetting the throttle, etc.,would make the make the codes go away permenantly. P0134 would come back after 2 starts. And looking at the OBC, I was only getting 15mpg. The original aging code and sensor location never came back. So I put my original O2 sensors back and haven’t had any trouble since.

Things I noticed about the cheap sensors:

• They made no differentiation between before or after cat sensor —all were the same, in the same boxes with the same color connectors. The original sensors are colored black or gray depending their place in the exhaust stream.The site indicated there was no difference between the before and after cat sensors, and that may practically be the case for the ’99 996 and earlier Porsches, but mine year at least has different plug colors and different part numbers.
• The sensors plug right in without a problem—no wiring or cutting of the original plug or harness.
• The packaging seemed good, but the sensors did not have the rainbow of discoloration from metal heating that you normally see in even a new O2 sensor. I don’t know if this discoloration is an artifact of manufacturing or testing, but it is definitely not there.
• I suspect the quality control is a bit lax and these end up being tested by the end user. There is not “tested by” info in the box—maybe this is typical even for OEM.
• There is a return and replacement policy, but before contacting them about the problem, they want me to run a series of tests on the sensors—send video of a voltmeter between sensor wire and ground while the car is running. I understand why they do this, but it is pretty clear to me that they sent me two bad sensors, and who knows what will happen to the other two. What a pain, not worth the time.

I am no expert, and have a sample size of 4 sensors, but a 50% failure rate seems a bit high. I may contact the seller or manufacturer directly and see if they will set things right, but when the “aging sensor” code comes back I’ll just replace that single one with an OEM. This is my experience, but in this case cheap is not worth the headache.

Ahsai

Always use Bosch O2 sensors (<$100 each). Pretty cheap from Amazon.

Paul Waterloo

Yep, throw those in the garbage and replace the other three, and don't look back or talk to the company that sold them to you or made them. Do it now before it affects your cat.

Device2

Well as the old saying goes "if you go cheap it will cost you twice as much in the end."Listen to Ahsai and go to Amazon and grab yourself a nice set of the Bosh O2 sensors for a sensible price.

Mark Hutchins

Have a 2002 Boxster Base and had to replace one Oxy sensor. Went to Rockauto and they had the Discount or Chinese made ones for like you say 4 for the price of one.... A caption got me. (it is better to replace them all so the computer can run at the same speed)... I just spent the day at California Smog Shops trying to run down the problem and after I got home, Looked this up in the Porsche forum to see if the cheap sensors could be the issue. They failed massively and the guy said "maybe the computer needs to get used to them"..... 120 mile or more.... Well, 120 miles out I got another failure light.... and I'm sure I know the problem. No more Cheap Oxy Sensors for me or the Machine.... Wasted a day chasing that 20 bucks....

yelcab

It's a joke when the box says "Each component is precision built for exact replacement"
If it does not say Bosch, pass and go straight to the garbage can.
Even Bosch has fake sensors now.

Flat6 Innovations

You bought these expecting a satisfactory result?