Fault P2189 After Coil Replacement

[jfoxny]

A couple of months ago my CEL came on (2006 C2) and started flashing while driving on the highway. The car ran really rough so I called Porsche road side assistance and they told me even though the light was flashing I could drive it to the dealer. So, I did (about 30 miles).  

 

Turns out that two of my coils were cracked.  The dealer ended up replacing all six coils under warranty (I guess there was some sort of informal recall on them).  A couple of days later my CEL came on again so I went back to the dealer.

 

The dealer scanned the car and said that the fault was something to do with "the fuel mixture being too lean at idle." However, they could not reproduce it and sent me on my way.  Just yesterday, the CEL came back on again.

 

Time time I scanned it myself with a Durametric tool. The fault appears to be the same faults that the dealer found:

 

P2189 - Oxy. sensor control. RKAT bank 2 range near idle speed

P2187 - Oxy. sensor control. RKAT bank 1 range near idle speed

 

 

I read through the forums and saw some references to a loose oil cap being at fault.  I checked that and it's quite tight. So, now I'm left wondering what else it could be.  Specifically, I'm wondering if it might be related to the coil replacement or to the fact that I drove it with the cracked coils.  Anybody have any ideas?

 

Thanks

Jason

Edited January 15, 2015 by jfoxny

[Loren]

You need to find out whether the FRAU readings are above or below limits to further diagnose.

Those numbers will tell you whether to look for an intake leak, or fuel pressure issue, or MAF isssue.

[jfoxny]

Thanks for the response, Loren. Is this something I can determine using the Durametric tool?

 

When I look at the "freeze frame" information regarding the faults for relevant information, I see the following:

 

Short Term Fuel Trim Bank 1 = -4%

Long Term Fuel Trim Bank 1 = 0

Short Term Fuel Trim Bank 2 = -3 %

Long Term Fuel Trim Bank 2 = 3%

Air Flow Rate from Mass Air Flow Sensor = 4 g/s

 

...and when I examine the "actual values" using the Durametric tool I get:

 

Fuel trim adaption close to idle (RKAT) = 3.656%

 

However, it's unclear to me how this feature of the Durametic works. Are you supposed to use it with the car running or is it showing me the last recorded actual values?

 

Jason

Edited January 15, 2015 by jfoxny

[jfoxny]

One thing I failed to mention is that after I brought the car in to diagnose the CEL (post-coil replacement), I noticed that when the car starts to idle the revs rise slightly before falling into idle.  I thought at the time that perhaps the tech adjusted something to try to prevent the fault in the future but I know it did not do that before.  Not sure if it's related or not.  

Edited January 15, 2015 by jfoxny