Hey all, seeking advice.

Background: I recently purchased a 2015 Porsche Cayman Base with 75,145 miles. The dealer performed a 10,000-mile maintenance before delivery (Oil change). Shortly after, I noticed my steering was squeaking and a hanging wire in the glove box and took the car to a Porsche Service Center. They recommended an 80,000-mile maintenance, during which they found misfires in cylinders 1 and 4. They claimed to have replaced the spark plugs as apart of the 80k maintenance and recommended a transmission fluid change as they had no record of the car having one, costing $1,031. The 80,000-mile maintenance cost $2,561 .

Photo of error codes from the first service center:



Current Situation: Less than 4 days later, I turned on the vehicle to a "Engine Control Fault, Consult a workshop, Driving permitted".


This time I took the car back to the original dealer as I remembered I was given a limited power train warranty for 6 months OR 6k miles (whichever comes first) with a $50 deductible. They charged $329 for diagnostics. After initial diagnosis, the advisor said, "We have two cylinders misfiring, we are going to swap 4 to 3 and 4 to 6 to see if the same cylinder misfire returns. My technician is requesting to take the vehicle on an overnight extended test drive as part of the quality control check."

They kept the vehicle overnight, got a text next morning, "No faults have and my shop foreman would like to continue driving the vehicle periodically throughout the day." That afternoon, "No faults have returned and my technician would like to take the vehicle for one more night! I will circle in the morning with another update!"

Then the following morning, "While no faults have returned. My shop foremen mentioned the vehicle feels like it is running rough or on the verge of a misfire. He would like to perform a leak down/compression test on all cylinders as part of the diagnosis, the cost of this would be an additional $987.00."

They performed a leak-down compression test ($987) which they said passed with flying colors and they replaced the spark plugs again. The dealer provided a photo of the spark plugs they pulled out which should be a week old. They appeared dirty and eroded, suggesting the first service center may not have replaced them. The dealer claims the coil packs were replaced in 2023 about 15,000 miles ago and that they have minimal wear and tear and don't need to be replaced. They claim the diagnosis is not covered under the warranty, and that they can't replace the coil packs since they have to provide a report to the warranty company which proves exactly whats failing and the coil packs are fine. They still have my car, "vehicle is currently not misfiring what so ever. We would like to let the vehicle sit over the weekend and perform one final quality control check before releasing it back to you."

"1 Week Old" Spark Plugs:



I really don't know who to believe anymore. I'm 22 and this is my first Porsche, I feel like I'm being taken advantage of and trying so hard to just get this resolved but seeking advise because I can't keep dumping money into this car. I have not taken it to a private guy because I wanted to get a good baseline from Porsche directly and then move to private.

What do I do?

I really think the coil packs need to be replaced. Do I push for them to be replaced under the warranty or do I go and get it done privately?

Is there any other diagnostics that should be done to rule things out?

Any advice/experience on extended warranty companies I should look into?

Costs Incurred so far:

• $1,031 for transmission fluid
• $2,561 for 80,000-mile maintenance
• $329 for diagnostics
• $987 for leak-down compression test

Attachments:

• Photos of spark plugs from the second service visit
• Service reports from the initial service center
• Carfax report
• Limited Warranty Terms
• Dash Engine Error Code
• Initial Misfire Codes

 

Wow I'm so sorry but it seems like you've been taken for a ride. I think you're on the right path. Misfires are almost always coil packs. I had the original coil packs fail one by one within the first ~50k miles of ownership. I now replace them on the same interval as sparkplugs and haven't had a problem since.

 

Thanks for the advise. Now it’s just pushing the dealer enough to do it under the warranty, which you’d like theoretically if I didn’t get thrown around and the spark plugs were actually replaced both times the justification for replacing the coil packs would be there. But you know, that would be too easy 😅

 

I had a couple negative dealer experiences which pushed me to start DIY-ing basic maintenance. If you have the garage space I would highly recommend it.

 

Small claims court. You have a valid powertrain warranty? I think your engine is covered.

 

Sorry to hear about such a horror story.
IMO sounds like a simple spark plug & Coil Pack change would've resolved the original problem report.

For a comparo here's a pic of my old spark plugs changed out last Oct. 2024.
They were 5yrs + 3mo old and had 21,665 miles on 'em. (DIY cost from FCP Euro was $289 + my time ..for the entire job).

 

Thank you for the pics and the diagram, super helpful! I am slowly getting more and more confidence to just do this myself. I was looking into getting the Durametric reader too, so I can read my own codes. I’m sure there’s a post on this forum, but is there anything special post install of the coil packs and plugs I need to do?

 

Also check the odometer to see how many miles were put on the car during those "extended test drives." I understand a shop wanting to keep a car overnight so they can see true cold-start behavior, and I can understand technicians test-driving a car before and after a service/repair, but I just don't trust the "Let us keep it and drive it" mentality. There are too many stories out there about technicians joy-riding in customers' cars with disastrous outcomes.

 

Yikes, thanks for this info too. I was hesitant on what the advisor wanted when he asked to take it for an overnight test drive. I asked him how many miles they would put on it. Claimed the technician lives about 20 miles from the dealership. I will add this to the list of things to check when I get the car back. Nightmare 👀

 

$226 for the tire sealant seems very high to me - even for terra-s from a dealer

It doesn't sound like they were wrong to check and replace spark plugs before coil packs if they only had 15k on them and it sounds like they found the issue after swapping coil packs out to check.

If you DIY in the future you can get coils (beru) for around ~$30-40 and spark plugs (bosch) for around ~$5 each. Porsche branded bosch plugs are more expensive though (I think around $30)

Though doing the coils now wouldn't hurt anything, based on what I've read here I would just run a fuel system/injector cleaner (like Keropur or Techron) annually, use quality premium fuel, and in ~40k miles change out the plugs again.

Maybe hit redline in the most aggressive sport mode on your car a few times while under warranty if you do think there is an issue with the coils

 

Nope, just the Service Interval update to the PCM via your code reader device.
Otherwise you'll get another nag message on the dash on start-up at some point.

Clear any current codes first, do the deed, set the new Service Interval date and GO.
N' coil packs are easy to replace. Spark Plugs are a bit more challenging but very doable with a couple of specialized tools.
N' having the car elevated a bit helps (e.g. QuickJack), but not absolutely necessary.

You can do it.