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2008 check engine light and now I have an erratic idol.

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So I am new to the Porsche world, but not new to German built vehicles. I have an 08 Cayenne (82k miles) I picked up (in perfect condition) with all the service history done at the local Porsche dealer. The last service was the 75k. Any way, I thought I would run some "Seafoam Motor Treatment" thru the fuel system and now (2 days later) I have a check engine light, with an erratic idle (also a pinging between 3k and 4k rpm).

Anyone have any idea as to what could be the cause of the idle and pinging. I plan on getting the codes read tomorrow, but just thought I would see if anybody had any ideas.

By the way, I absolutely love this rig and am not scared by the hefty price tag that comes along with the care and maintenance of the Porsche. [emoji10]

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  • Admin

If you have a check engine light then you have fault code(s).

Until we see the fault codes it would all be guesses.


Make sure you use Durametric or a Porsche diagnostic tool (PIWIS or PIWIS 2) so you also get any pending fault codes.

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Appreciate the info. I will be getting the codes checked tomorrow. Just thought I would see if anyone had ever had/heard of the same issues.


As Loren pointed out, without the codes, anything would be a guess.

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  • 4 weeks later...

See if she runs/idles better after pulling the main fuel pump fuse No. 14 in the engine driver's side fuse box.  If she runs on the secondary pump better at low speeds, you may have clogged up your fuel filter with the crud that Seafoam loosens up.  It's best to have a vac line suck it into the intake, but it really smokes.  Might also try a e-throttle calibration if carbon was holding the butterfly flap open a bit.  Adjustment instructions are in the owners manual.  How do the spark plugs look?

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