At 9931 miles on the my 2017 991.2 C2 (and just over a month off of warranty), I did a spark plug change, oil change, brake fluid flush and air filter change. Yesterday, after putting about 35 miles on the car, I did some "spirited driving" in Sport Plus on a remote local road thru the hills not far from my house. As I arrived at the rural highway that leads home, the check engine light came on and the multi-function display read "Engine Control Fault, Consult with Shop, Driving Permitted". The car felt and sounded like it was misfiring. Shortly, I saw a PSM warning flash and the PSM "off" light on the console lit up (I have never driven with that off). That didn't last long and those items went away and it was back to the previous warning (driving permitted). In a short while, the warning changed again to "PDK Trans overheating, reduce engine load" so I pulled over and shut off the car. From the time the warnings started, I drove between 30 and 50 MPH as there was heavy traffic. After sitting a few minutes deciding what to do (late Friday afternoon), I restarted it and the original warning came back on "driving permitted" so I started off again. After another 1/2 mile, the misfiring seemed worse so, even though I was only about a mile from home, I decided to pull over and call for a tow. I had it towed to my house hoping I could use my iCarsoft to diagnose and repair it myself. I did the diagnostics today and one of the faults is 007010 "check engine control unit fault memory content". From my research and the way the car was driving, I am thinking MAYBE it is a bad ECU. There is also a PDK TCU but I don't know if it would have caused the misfiring symptoms. I cannot see any reason it would be related to the spark plug change but am open to thoughts about that. Also, I cannot find a stock ECU replacement online, only upgraded and/or tuned ones. ANY input is welcome, I'm not sure if I trust my ECU evaluation so am considering taking it to a shop (ugh!). I also got codes of 00A008 "PSM failure", 00A016 "check engine" but not all the codes I found begin with a letter and my iCarsoft OBD is not giving me options to explain them. It only wants to see a letter, followed by 4 letters or digits. Thanks in advance for your input.

 

I can only think this must be related to the work you have done since it happened right after. You did work on the ignition system and now have a misfire. Go back and double check everything. Good luck.

 

Like D2M said, double triple check your work. Make sure coils were clicked in snugly and all plugs are tight and torqued.

May I ask if you have extended warranty since original warranty is out, if no why not? These things can get expansive quick if/when something like this goes wrong.

I am hoping it has something to do with your spark plug change, hopefully. Good luck and keep us posted

 

Make sure the connectors that go on the coils are fully seated. I had the exact symptoms you describe happen to a buddy's car after I did the plugs. I thought I had wrecked his engine. Turns out one of the connectors wasn't pushed on all the way.

 

I'm not too proud to say this is good advice and my next step unless someone shares the silver bullet secret. I swear I heard each coil pack connector click but...
good news is, having recently done it, I can do it in less time. And thanks for the replies. I was thinking maybe a misfiring plug could cause the ECU to fritz?

 

Thanks. Why not, unknown. Probably thought P cars would be good enough not to need one. Four years ownership and less than 10k miles, I would hope...

 

you should be fine.. but with that low mileage you can get 100% peace of mind for 5-6 yrs for a mere $2500 (Fidelity Platinum coverage)

 

I don't know: with all those codes, seemingly unconnected to spark plugs and brakes and oil, I would think that somehow you ran the battery down too low, and it threw a bunch of electrical codes your way. I don't see how changing spark plugs would affect ECU or PDK or PSM, which is why it sounds like an electrical problem, possibly from running diagnostics without enough voltage into the electrical system? I would just fully charge the battery, and drive it around the block to see what happens, after clearing the codes, and see if they recur, or not.

 

Agree, check your battery. Already 5 years old, could be it…..

 

good point

 

Maybe replace coil packs? Retorque plugs? Nothing was cross threaded? Don’t know if it’s OK to remove plugs to look at and reinstall but if one looks off then you can replace that one. Probably not ok to drive on back roads with rear bumper off as a test drive but only you know your area. Best of luck. Please report back to update this so we all can learn what solution is.

 

WP0, this makes sense. I've worked on cars with electrical faults and the source was low voltage across the system.

Great alternative and easy check!

 

Guys, Much like the OP I am also coming out of a 991,2 out of warranty and need to do plugs soon; with 25k I've been looking into the Fidelity Warranty.

This thread is pushing me towards it!

 

I had a similar issue. I changed the plugs on my 2014 C2 but did not change the coil packs. A few days later I had misfiring on one cylinder. I replaced all coil packs and engine has worked fine ever since. The car had about 20k miles at the time. Buy the replacement parts from FCP Euro and the parts will be nearly free (you pay the return shipping) should one go bad again.

 

If a 5-year-old battery could do that, I think it would be pretty obvious. You have a bad coil or a loose connection.