Need to replace the precatalyst O2 sensor for cylinders 4-6. Dumb question, but would rather be sure. Which side of the motor? Thanks.

 

Bentley shows the (USA car) driver's side cylinders as 4-6.

Added: Here is a cut/paste from something I posted on this a while back.

From page 395 of the Bosch Automotive Handbook, 5th edition:

Number the cylinders
(DIN 73021)

[Applies to motor vehicles only. For internal combustion engines for general and marine use, the reverse direction (as viewed looking at the power-output end) is standardized (ISO 1204 and 1205, DIN 6265).]

The cylinders are numbered consecutively 1, 2, 3, etc. in the order in which they would be intersected by an imaginary reference plane. As viewed looking at the end of the engine opposite the power-out-put end. This plane is located to the left when numbering begins; the numerical assignments the proceed clockwise around the longitudinal axis of the engine [ fiqures are referenced ]. If there is more than one cylinder in a reference plane, the cylinder nearest the observer is assigned the number 1, with consecutive numbers being assigned to the following cylinders. Cylinder 1 is to be identified by the number 1.

The figure for a flat engine shows the #1 cylinder is the when looking at the engine from the power output end is located on the right bank at the furtherest cylinder from the power output end.

For the Boxster/Cayman cars this would make the #1 cylinder the cylinder immediately behind the passenger (USA cars, left hand drive).

For 996 cars this would make the #1 cylinder the cylinder furthest away from the driver (USA cars, left hand drive) on the cylinder bank on the driver's side of the car.

 

Thank you.

 

I wish all my Boxster repairs were this easy...30 min total. Car has no hesitation anymore.

 

Thanks for the update. Glad it went well.

Don't mean to be a buzz killer but generally sensors should be replaced in pairs.

(If old enough all 4 should be replaced. My experience is it can positively effect how the engine runs.)

Unless the sensors are relatively new and one just suffered from "infant death" old sensors age and slow down.

If just one sensor is replaced the two banks can experience a difference in fueling that is due to the differences in sensors and not due to real differences between the banks.

'course, there is an understandable reluctance to replace what appears to be a working sensor.

 

All of that is understood, and I thank you for your amazing generosity with your experience and knowledge. I wish I lived near you, seems like it would be quite educational. My Boxster is now running like it should. Time to tackle the extremely sluggish 1985 3.2 Carrera...

 

Thanks for the kind words. I've received some help from here and other places over the years and in some way just trying to pay forward for the help I received.

Living near me would be boring. I spend most of my time at the office with no time to do much of anything else. (Since returning to work after a layoff my managers keep me neck deep in work.) My routine consists of get up and go to work. Come home and go to bed. My social life is limited to exchanging small talk with the gas station clerks when I stop to fill up one of the cars. Saturday I do laundry and sleep. Sunday I just sleep.

 

Of course after I proclaimed victory, and the Boxster was running very well.... it threw another CEL this time the codes were 1126 and 1133. So at least it is not the same oxygen sensor that was replaced. I have cleared the codes and am awaiting their return, to make sure this is a real issue. The codes are for both banks of cylinders...and are referred to as oxygen sensing adaptations. So, I guess it could be some calibration procedure for the new oxygen sensor, maybe?? Interesting side note, when I posted this thread initially asking which side the 4-6 cylinders reside, I also sent a text to the Porsche dealer service manager. He responded, after I replaced the sensor, and claimed the 4-6 cylinders were passenger side.

 

https://sites.google.com/site/mikefo...side-is-bank-1

And O2 sensors references are here.

 

Awesome info, thanks! Just glad the Porsche service manager didn't respond to my inquiry for 24 hrs. If he would have given me the info in the normal texting turn around time, I would have replaced the wrong one, and never made this initial post.

 

Please be very careful with the part number/year and the brand.
Some sites like Rock Auto have incorrect info.
The generally approved brand is Bosch. As previously noted, doing all 4 with the same brand at the same time seems to work best.
Don't forget to check coils for hairline cracks, spark plug tubes for leaks and maybe do plugs 'while you are in there'
Otherwise you may be haunted by codes for a while.
If you have Durametric or similar you can easily check O2 sensor performance, but if they are old/unknown/off brands/one is failing - suggest you do everything once !
See photo of defective coils here:
https://rennlist.com/forums/boxster-...-smoothly.html
Long before they got this bad, hairline cracks would have been visible with a lens in bright light.

 

Plugs, cylinder tubes, and coils were all replaced a month ago.