CEL Nightmare

[Kojiro]

Recently my CEL light came on, and I didn't worry much about it because it went off shortly after. But then came on again, and went off again, so I was pretty sure it was probably some small sensor issue like an O2 sensor. I didn't do anything about it for a while because I only really dive the vehicle a few blocks to work and maybe the occasional drive other than that. So then it came on and didn't go back off, but in waiting for it to go back off, at a few stop lights it started blinking, I knew what that meant and started to worry. It has also started giving clouds of white smoke on start much too often. I took it to get the engine codes and here is what it came up with. I don't have a Porsche dealership within hundreds of miles of me and so I mostly DIY everything on it. I am probably going to replace the AOS, and change the oil at the same time soon. Although I was wondering if anyone could help me pinpoint the problems better.

Here is the list that the OBD II readout gave:

P1121 - Oxygen Sensor Heating 2 Behind Catalytic Converter – Below Lower Threshold

P0440 - Fuel Tank Ventilation System - Above Limit

P0160 - Oxygen Sensor After Catalytic Converter (Cylinders 4 - 6) - Interruption of Signal

P0150 - Oxygen Sensor Ahead of Catalytic Converter (Cylinders 4 - 6) - Intercore Short Circuit or Limited

P1126 - Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Rich Threshold

P1124 - Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold

P0300 - Misfire Damaging to Catalytic Converter

P0306 - Misfire, Cylinder 6, Damaging to Catalytic Converter

P0304 - Misfire, Cylinder 4, Damaging to Catalytic Converter

P0305 - Misfire, Cylinder 5, Damaging to Catalytic Converter

P1319 - Misfire, Emission Relevant

P1318 - Misfire, Cylinder 6, Emission Relevant

P1316 - Misfire, Cylinder 4, Emission Relevant

[Loren]

Exact model and year of your car please...

[Kojiro]

Exact model and year of your car please...

Sorry, I actually was planning on putting that in there last, but forgot. :D

It's a '98 Boxster 986 2.5L

[Loren]

If your CEL is flashing you should not drive the car.

Check your oil for coolant - and check your coolant tank for oil.

[Kojiro]

If your CEL is flashing you should not drive the car.

Check your oil for coolant - and check your coolant tank for oil.

If there is one in the other, what does that mean? And what causes this? (I haven't had a chance to check yet.)

[Loren]

If there is oil in your coolant - or if there is coolant in your oil then you likely have a bad head gasket or a cracked cylinder liner. Which is major - otherwise it could be just a bad AOS.

I hope it is just an AOS but you need to look at the coolant and oil to be sure.

[Kojiro]

Would the oil in the coolant be visible from the coolant tank window or anywhere else? Or would I have to drain the coolant and oil to see if one has the other?

[Loren]

You would see the oil in the tank.

As far as coolant n the oil - you might get lucky if you remove the filter and pour the cup or so if oil into a glass container to inspect.

If it is okay just pour it back in.

[phillipj]

If there is coolant in your oil your dipstick will look like it has pancake batter on it. :o Pray this is not what you find :huh:

Edited October 21, 2009 by phillipj

[Kojiro]

My coolant tank has always been a slightly brownish color, and I was told by a dealership that the coolant is sometimes that color, and the dipstick comes out smooth, and contains only oil, the coolant looks pretty clear when I look into it from the coolant cap. Although i have yet to take the oil filter out to inspect it. I will post more details once I do.

Edited October 22, 2009 by Kojiro

[phillipj]

Great news :D Hopefully just your AOS. A real PITA on a 996. But you can do it. Great to hear you have no intermix issues. :clapping: Let us know what you find.

[txhokie4life]

My coolant tank has always been a slightly brownish color, and I was told by a dealership that the coolant is sometimes that color, and the dipstick comes out smooth, and contains only oil, the coolant looks pretty clear when I look into it from the coolant cap. Although i have yet to take the oil filter out to inspect it. I will post more details once I do.

If in doubt -- stick in a turkey baster and suck some coolant out and look at it.

mike

[Kojiro]

I really hate when people never resolve their threads when they fix the problem, and so I am not going to do that.

I just yesterday went to a bigger city (in a different vehicle) and got a new AOS and the tube that goes from it to the throttle body. I installed the AOS today, and now the car runs GREAT, I mean like it did a year ago. It idles perfectly now at ~800, never chokes the engine to weird RPM's when I am not doing anything anymore, and no more smoke!

Granted the AOS was a PITA to install, it was worth it, and it was something I was able to tackle alone in a few hours. Most of the hard work is getting some tubes to go on/come off of their respective parts, but other than that it is pretty simple. The first time I started it after I installed it, there was smoke, and it wasn't just on startup, it was a steady small stream of it for a few seconds, but once it was burnt off, I took it for a test drive, and I have started it about 5 times today after that and it has ran great all day/night! Thanks for all of the help everyone.

[phillipj]

Awesome! Thats is great news and congrats on doing the work yourself :clapping: :clapping: :clapping:

:thumbup:

[mikefocke]

You may want to clean the throttle body, the intake tube and the MAF.

They all could have gotten seriously fouled.

[Kojiro]

So I had been planning on cleaning the MAF once I got a chance to pick up a security torx of the right size, but the car has been driving great, idling great, etc. The only thing is that it seems less powerful than it did with the old AOS, and the exhaust sound has changed, it is much quieter (which I like) but it sounds much more airy/raspy (which I don't like as much.) However, considering the circumstances, I was glad the CEL light was off and the car was running fine, until today... I was driving home from work, and as I was pulling up into the driveway the CEL came on. Since I was already home, I parked it and just now got a chance to get the codes (a bit later, but only one start in between to drive a very short distance to get the code,) and it has nine codes, and a few look familiar :( Here they are:

1121 - Oxygen Sensor Heating 2 Behind Catalytic Converter – Below Lower Threshold

0160 -  Oxygen Sensor After Catalytic Converter (Cylinders 4 - 6) - Interruption of Signal

0150 - Oxygen Sensor Ahead of Catalytic Converter (Cylinders 4 - 6) - Intercore Short Circuit or Limited

1126 - Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Rich Threshold

1124 - Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold

0300 - Misfire Damaging to Catalytic Converter

0306 - Misfire, Cylinder 6, Damaging to Catalytic Converter

0304 - Misfire, Cylinder 4, Damaging to Catalytic Converter

0305 - Misfire, Cylinder 5, Damaging to Catalytic Converter

Also, another note, when I started it to go get the CEL codes, and was leaving my neighborhood, it started hanging at 2-3k during idle until I drove for a few minutes (which was what I had just fixed, or so I thought.) any ideas? Could this just be that I should have cleaned the MAF and the mix is too rich now? Because my Oxygen sensors like to freak out in groups...