Lambda sensors

[tim.barnett]

Hi all

I'm new to this forum and wonder whether anyone can give me some advice about a recurrent problem I am having in relation to lambda sensors (possibly the MAF sensor or exhaust system too?)

I have a 986 Boxster S, first registered 2002, it's done 60,000 miles, I have owned the car for over 2 years and done about 18,000 miles.

The problem is that every few months, the emission control warning light comes on on the dashboard - this has happened about 5 times in 18 months - and every time, the Durametrics diagnostic software always comes up with the same code: P2096 "Oxygen sensor - ageing, bank 1." When the light comes on, it always happens not long into a journey (within the first 10 miles or so).

In addition to the Durametrics software, my mechanic also used a handheld device that measured various readouts when I revved the engine, and using this we came to the conclusion that it was the bank 1 (right hand side) rear sensor (after the catalytic converter) that was the problem.

However, wanting to knock the problem on the head, I have had all 4 sensors replaced.

However, the light has since come on again and the same fault code comes up: P2096 "Oxygen sensor, ageing, bank 1".

My mechanic says that I could have one of three problems:

1) one of the new lambda sensors is faulty (I have no idea how this could be checked)

2) the problem is not the lambdas but is in fact (despite the fault code reading) the MAF sensor

3) there is a very small leak somewhere in the engine or exhaust system that is causing this intermittent fault message to come up

There has been no noticeable change in the performance of the car throughout this whole issue - it still idles fine, I get about 300 miles from a tank of fuel, it still seems to sound good, so I don't know where to go next.

Can anyone out there tell me:

1) is this a common problem with 986s

2) if there is no change in the performance of the car, then is this recurrent issue something that one should simply accept is a fact of 986 ownership, or does it suggest a bigger problem that does need to be properly diagnosed?

3) if the problem is indeed the MAF and not the lambdas, then to what extent is it surprising that the fault code read out has always said "oxygen sensor - ageing, bank 1" and not mentioned anything about the MAF sensor?

..and of course if anyone has any other useful info on this, I'd be grateful.

Thank you.
TB

[Topless]

"Aging sensor" codes usually indicate a problem directly related to the sensor, sensor wiring harness or DME issues and not a bad MAF or intake/exhaust air leak. Trace the wiring to see if has been damaged or pinched. Sometimes rodents will chew wiring as it passes through a bulkhead or firewall. There is also a circuit test I have seen in the past from DME to sensor which will help isolate the problem. A quick online search came up empty though.

After a little digging I found this most unusual error code P2096- "Post catalyst fuel trim system too lean bank 1" This is very different than "aging sensor". I would clear it and if it comes back, confirm that it is the very same error code. If it is and your sensors are new I suspect an exhaust system leak on that bank near the sensor. A small hole in the cat would do it.


I hope this helps some.

[mikefocke]

O2 sensors are subject to aging...one week I replaced a Boxster one and a Honda one days apart. And yes 'aging" is a common fault code for something that sits in the exhaust stream, it was mine at around 50k. Replaced and never had a problem again. Usually the front right side goes first (looking from the rear).

I'm assuming you used the correct sensors when you replaced them?

The fault code you describe is not one in my DME book so I'm unable to help further as I don't know either where the fault is occurring nor why. If you doubt the sensors, swap 2 of the new ones and see if the fault follows the swap or stays on the original side.