front O2 Sensor location?

[Paul Whyte]

Hi folks,

Firstly i have a 99 boxster, My car failed its test on emissions so I changed my o2 sensors, however it has still failed its retest on emissions,

I am aware I only need to replace the front 2 sensors (pre cat) not the post cat sensors (as I am not receiving any error codes)

Stupidly I think I may have replaced the rear ones and left the old front ones in place! can someone kindly post a photo or a diagram showing me where the front sensors are, I plan on swapping them round and hope this remedies the emissions fault.

I am angry with myself as it was a nightmare getting them out, and I needn't have bothered as they are fine, I am hoping I did replace the rear ones now, as if I have replaced the front ones, then there is a more serious issue.

Thanks,

Paul

[JFP in PA]

Shown here is the catalytic converter and its two oxygen sensors (red arrow shows the front, yellow shows the rear). The small black connector, shown by the green arrow, attaches the sensor the wire harness and can easily be removed by pushing the release tab. I have often found that the new O2 sensors come with the correct plug, but sometimes the cable is way too long. If this is the case, then secure the cable with a nylon zip-tie. Make sure that the cable is not located anywhere near any exhaust components - you don't want the heat melting the cable to the O2 sensor. The photo inset shows the special tool that is sometimes required to remove O2 sensors in hard-to-reach places

[extanker]

put a scan tool on the car and look for the problem

[Paul Whyte]

Yup, I replaced the worng ones. haha, I am relieved and angry with myself, what a school boy error!

I have purchased a laptop USB tool and some software off ebay for diagnostic and code resetting etc... where is the OBD2 port please?

[extanker]

on a US car its on the lower dash near where the drivers knees would be

[Paul Whyte]

Many thanks for your help guys, much appreciated.

Mines UK spec, I shall have a look.

[JFP in PA]

It will be by the other knee..............

[Paul Whyte]

Hi folks,

I can only find one sensor each side of the exhaust system, in the location by the yellow arrow, I have a 99 boxster 2.5.

Can someone please post a photo of the standard exhaust system on a 986. As I am pretty sure mine only has two O2 sensors on it.

Also, when facing the rear of the car, the sensor location is infront of the cat. (upstream - towards the engine) these are ther ones I have replaced.

My car has still failed on emissions, I ran a diagnostics check on the car, and the readout states voltage going to the sensor, is the readout on OBD2 showing the readout from the cat, or from the ECU? basically, how do I check to see if they are working,

If anyone can help me with any recommendations for emission failures I would be most grateful. the garage said I may have a hole in the exhaust, I saw what looks like a small hole in the large back box where the two exhaust pipes enter either side.... would this effect at all?

thanks,
Paul.

[Frodo]

As I have stated many times in the past, I'm no expert here. (Long-time forum members will attest to this fact! )

Having said that, however, I did take a look at the description for O2 sensors at both pelicanparts.com and in my Bentley Service Manual (MY 1997-2004). They seem to clearly indicate the presence of 4 sensors on all models, 2 pre-cat and 2 post-cat. Have you looked closely at the Pelican Parts picture above, and closely at the exhaust arrangement on your car?