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WD-40
Newbie


Joined: 31 Jan 2019
Posts: 13



PostPosted: Mon Mar 04, 2019 10:03 am    Post subject: Check engine light (again) Reply with quote

A little while ago I had the check engine light come on. My car was already booked in to my local indy for a service, so I asked them to check it out. They found a fault code for an O2 sensor but the tests for this were ok. They noted that the car is running aftermarket cats which is what they concluded to be the fault at the time.

Now, 500 miles later, the light has come on again. It may or may not be the same fault but sounds like in all likelihood it would be - which I guess means it would be another hour or two's labour to make that diagnosis.

Any thoughts on what I can do to avoid having to set up a monthly visit and direct debit to my local (half an hour away) indy, to diagnose / clear the fault? Or avoid replacing the cats - or am I just going to have to bite the bullet...
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WD-40
Newbie


Joined: 31 Jan 2019
Posts: 13



PostPosted: Mon Mar 04, 2019 1:26 pm    Post subject: Reply with quote

Not sure if it makes any difference, but the cats are X-pipe 200 Cell Sports Cats, from Top Gear - anyone else had similar issues after installing these?
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NXI20
Paul Ricard


Joined: 02 Feb 2008
Posts: 3362
Location: South Bucks

2004 Porsche 996 GT3 Mk2

PostPosted: Mon Mar 04, 2019 1:45 pm    Post subject: Reply with quote

2 options:

1) Disconnect your battery for 20 minutes - that clears the fault

2) Buy a cheap code reader that can also clear faults
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deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6523
Location: Brighton


PostPosted: Mon Mar 04, 2019 8:57 pm    Post subject: Reply with quote

Need a little more info .. pre or post cat lambda sensor ..

What was the fault code ?

Post cat and you are looking for switching on the sensor to indicate a worn or tired cat ..

A flat line either high or low will indicate a rich or a lean mixture .. a crack in the cat close to the exhaust can cause one of these .

If pre cat is it only x1 bank ?

If both then maf .. if a single then again if rich a leaking injector .. if lean then an air leak.
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WD-40
Newbie


Joined: 31 Jan 2019
Posts: 13



PostPosted: Tue Mar 05, 2019 9:35 am    Post subject: Reply with quote

I've just ordered a diagnostic code reader which will hopefully tell me what the fault code is and I can go from there.

If it is the O2 sensor then I'm minded to just clear it and motor on...
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deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6523
Location: Brighton


PostPosted: Tue Mar 05, 2019 8:07 pm    Post subject: Reply with quote

It all depends on what the fault code is .. i can advise better once i know as there are many different codes for different problems .. some can be ignored .
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MisterCorn
Long Beach


Joined: 08 Jan 2011
Posts: 6966
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Tue Mar 05, 2019 8:14 pm    Post subject: Reply with quote

If you are anywhere near Nottingham I'm happy to plug it in to my Durametric.

MC
 
  
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WD-40
Newbie


Joined: 31 Jan 2019
Posts: 13



PostPosted: Wed Mar 06, 2019 10:59 am    Post subject: Reply with quote

So I received my diagnostic code reader and it bought up the following fault code:

P2098 - Post catalyst fuel trim system too lean bank 2

There was also a 'pending' code of:

P0156 - O2 sensor circuit bank 2 sensor 2

As I said in my original post, my indy previously tested the O2 sensors and they were fine, so I've put my blinkers on and re-set the codes.

Please tell me if I'm being stupid and should get it checked out before something blows up...?
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deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6523
Location: Brighton


PostPosted: Wed Mar 06, 2019 8:48 pm    Post subject: Reply with quote

Post cat sensor too lean .. you have an exhaust leak young man , its drawing air in and giving the sensor a false reading .

It is possible its something else but ill give you a 90% chance its an exhaust leak .

You can clear the code but it will keep coming back ..

Ive found over the years the best way to prove this fault .. stick a smoke machine up the exhaust .. you will see the smoke come out close to the sensor .. worth getting a garage to have a look but its normally a new cat on that bank to repair .. welding never seems to work .
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MisterCorn
Long Beach


Joined: 08 Jan 2011
Posts: 6966
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Wed Mar 06, 2019 9:12 pm    Post subject: Reply with quote

I don't have a smoke machine, so I get a length of tubing, stick one end in my ear, wave the other end around the joints and listen for the leak.

MC
 
  
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