I would suggest that you get the codes from the dealer that caused the CEL to come on (twice now). Post the code here for the experts to weigh in on possible cause / fix from prior experiences. I would try and take the car to another dealer if there are options where you live, it sounds like the first dealer you went to is incompetent and/or not experienced enough in Hybrid troubleshooting to be able to diagnose / repair your "under warranty" situation.

Also, fill in your signature panel with your location / car details as that the info can help others with your problem.

 

I would definitely get them to write down the codes generated. So far in the last three months, we have had three check engine lights and other warning lights go off in our 2016 Sonata Plug-in.



First time, wife was told it was bad gas after check engine light thrown. Possible, but not likely since I buy Chevron which is top tier gas. Plus, it would seem to me that car would run poorly all the time on bad gas.



Second time I took the car in and had them write down the code. Car was idling rough. Engine light and multiple other warning lights, including the stability control warning light. Code P0335, crankshaft position sensor. Car still had rough idle when cold start after repair. Runs fine as the vehicle warms up.



Third time, no warning lights, but still rough idle when cold and now the car starts to miss severely until the engine warms up. Car runs fine with a warm engine. Took to the dealer and tech can find nothing wrong after keeping it over night.


Four time and very next day after just taking it in for the engine miss, the car throws a check engine light after a cold start and rough engine idle. This time a P0303 code. Tech replaces one ignition coil and plug assy. The car seems OK now.

 

I must commend you for your patience. As you saw in my post, my car also came up with P0303.

What I don't understand is why the tech just can't look up the service bulletin first and start from there. My car was in the shop for 5 hours until the SA called to ask if they can keep the car overnight.

 

An overlooked and cheap repair for a car shuttering when cold, is the temperature sensor. If it sends the wrong temp to the computer, the car runs poorly.

 

I dropped off the car at the same dealer again this morning as it's the only one in the area. Got a call back from the service advisor in the afternoon. The code is P0303, cylinder 3 misfire. He said the tech tried to replicate the issue but was unable to. He wants to try again in the morning tomorrow so I gave them permission to keep it overnight.

When I called to make today's appointment I told the advisor about this: cars(dot)com/articles/2016-hyundai-sonata-hybrid-engine-issue-1420684958695/ and asked if he could have the tech check it out.

I also found this thread: hyundai-forums(dot)com/sonata-all-hybrid-models-yf-lf/444849-2016-sonata-hybrid-cold-weather-mis-firing.html

The area where I am had a colder than average winter so the weather condition was similar to what other owners went through.

Btw, I looked at the invoice from the previous trip to the dealer. It says "scanned all systems and found a low voltage code in history. erased and re-scanned and no codes found. no further action needed." Does anyone know what this could entail?

When I dropped off the car this time, I asked the advisor to get me the code for the previous CEL incident. Hopefully, he'll be able to provide it.

 

Got the car back today. The tech couldn't duplicate the issue but called the corporate office to check. He was advised to replace all ignition coils after he provided them the scenario. The SA said it was an easy phone convo. I'm guessing that Hyundai is very well aware of this issue as there's a service bulletin. All in all, it was relatively painless compared to other cases I've read in this forum and other Hyundai forums. Hopefully, the issue has been resolved and CEL won't come back on again.

Thank you all for your insight and advice. This forum rocks!

 

Glad to hear a decent result in this case. Keep us updated on how sustainable it ends up being.

 

Hyundai should have approved the replacement of all four of my car's ignition coils, hopefully with improved parts. The tech probably never called Hyundai. So now I get to go through this again next winter.



The service manager sent me an E-mail after my review of their service. We will see if the service manager takes the initiative and calls Hyundai for approval to replacement the other three coils.

 

@marshallwa,

which dealer was that? pm me if you prefer. I often go to Eastside(Bellevue/Redmond/Kirkland/Issaquah). If the dealer is from that area and I need a repair, I'll avoid it.

If you haven't already, run your VIN here to see if there are recalls/safety issues: nhtsa(dot)gov/recalls

Here's another site that lists service bulletins: truedelta(dot)com/Hyundai-Sonata-tsbs-121,2016

The ignition coil service bulletins were issued July-September of 2016.

 

Good news! Hyundai has OK'd the replacement of the other 3 ignition coils. Hyundai told the service manager that the TSB has expired, but as a goodwill effort they would replace the other 3 coils. I don't know how a TSB expires, but at least the car is getting all the coils replaced.



Hopefully, the new coils are better then the old ones as the car has less than 11,000 miles on it, with even less miles on the engine.

 

Glad it worked out for you. Reminds me of when I had the MIL light come on in my '07 Accent and I brought it to the dealer. There was a TSB about the coils and the "advisor" tells me they will be replacing them for free, but it needs new plugs. I ask her how much for the plugs and she says $200. I tried to hold it back but had to laugh out loud in front of the others in the waiting area and told her I will go down the road to Advance Auto and get plugs for $3 each and put them in myself in 10 minutes with one hand tied behind my back and blindfolded. She tried to tell me how dangerous it was to drive with the old plugs in the car with new coils and how they should do it. I told her to tell the tech to button it all up and I will be leaving to get plugs on my own. I can't stand the way dealers try to take advantage of people with scare tactics and nonsense lies.