I have a 2017 Jetta with 67K miles. In the past year the CPU has coded 1,3,4 cylinder coil misfires at some point. The misfires were activating the check engine light. About the same time, I would hear a low engine knock around 30mph when slowly accelerating.
Before I spend the money to replace them, is it possible to test them to see if they're truly defective? If I do need to replace them, is it best to do all four? If I do need to replace them, do they need to be OEM or are after market acceptable?
Scotty says in your case some aftermarket coils are better than OEM at 7:27
https://youtu.be/21IUQM8X12s?si=gLKvoIlBmjjaHMAj
Thanks for the post. I'm honestly surprised at his feedback on OEM.
You are welcome. That was interesting for me too.
What are the actual codes? Misfires can have many different causes.
It's been a while since I had the codes checked but I think they were like P0301, P0303, P0304
Anything suspicious in live data like fuel trims out of whack? If you look up those codes online you'll find a list of potential causes.
TBH I wouldn't know. I don't have my own scan tool and wouldn't know what to look for. I'm currently trying to find the cause of my evap error code. I cleared the history last week and again today after replacing the gas cap. The same misfire codes also came back.
Unless anyone here has better ideas, it sounds like I'll need to pull the plugs and see if they're in good shape. If they are I guess I'll just need to replace the 3 coils. The car still only has 67k miles though.
I know you can use an ignition spark tester like (I think) an OEM 25069 to determine if the coil is firing... but that's all i do know but to be safe make sure to double check my facts
is it possible to test them to see if they're truly defective?
Yes. Please check the FAQ
