Multiple Misfires Errors following Coolant Pipe Replacement

[bmats]

I have a '05 Cayenne S. I changed my coolant pipes on 10/20/13 (followed the instructions in on this site) and I changed the spark plugs around Oct 2012 (less than 10k miles ago) using NGK BKR6EGP G-Power Spark Plugs.. I'm receiving the following multiple errors:

P0205 - Fuel Injector, Cylinder 5 - Open Circuit

P0300- Misfire Detection Checksum Error

P0304- Misfire Detection, Cylinder 4 (Bank 1)

P0305- Misfire Detection, Cylinder 5 (Bank 2)

P0406- Misfire Detection, Cylinder 6 (Bank 2)

P0308- Misfire Detection, Cylinder 8 (Bank 2)

My First thought was to switch out the spark plugs again and replace the fuel injector for Cylinder 5. However, before doing that I thought I would turn to this forum for suggestions on how to troubleshoot my issues...wondering if their could be other issues as hand that would cause these multiple errors.

If you think that changing out the spark plugs is a good next step, can anyone tell me what the recommended replacements are? A Porsche Certified mechanic said to use Bosche Platinum plugs and by not using them could cause misfires. Anyone agree with this assessment?

Thank you

[JFP in PA]

I have a '05 Cayenne S. I changed my coolant pipes on 10/20/13 (followed the instructions in on this site) and I changed the spark plugs around Oct 2012 (less than 10k miles ago) using NGK BKR6EGP G-Power Spark Plugs.. I'm receiving the following multiple errors:

P0205 - Fuel Injector, Cylinder 5 - Open Circuit

P0300- Misfire Detection Checksum Error

P0304- Misfire Detection, Cylinder 4 (Bank 1)

P0305- Misfire Detection, Cylinder 5 (Bank 2)

P0406- Misfire Detection, Cylinder 6 (Bank 2)

P0308- Misfire Detection, Cylinder 8 (Bank 2)

My First thought was to switch out the spark plugs again and replace the fuel injector for Cylinder 5. However, before doing that I thought I would turn to this forum for suggestions on how to troubleshoot my issues...wondering if their could be other issues as hand that would cause these multiple errors.

If you think that changing out the spark plugs is a good next step, can anyone tell me what the recommended replacements are? A Porsche Certified mechanic said to use Bosche Platinum plugs and by not using them could cause misfires. Anyone agree with this assessment?

Thank you

There should be no problems with the plugs you chose; but you may have disturbed or not correctly seated a wiring harness plug(s) on the engine. I would start by checking anything you moved or disconnected to make sure nothing has come loose.

[Stephtell]

Exactly my thought: either one or more electrical connections that aren't made properly or even a wire that's gone brittle and cracked during removal/installation?

I had an annoying misfire on my S6 after fitting new spark plugs and coils: turned out to be a spot of grease on the coiltube, cleaned it and no more misfire!

[PKN]

...and check/replace fuses 7 and 8 in the E box under the hood

Steve

[bmats]

Thanks for the help. I Discovered loose connection on cylinder 5 fuel injector. Easy enough fix. Thanks again.