P0302 misfire

Welcome...
Unfortunately, I'm on the left coast. If someone can't recommend an honest mechanic in your area - start calling around. Ask the shops how much they would charge you to do a comprehensive used car prepurchase evaluation. This sounds like something you need; a third party that has no skin in the game; and is willing to tell you the unvarnished truth. This usually cost $100 to $200. If the dealership didn't give you the carfax for the car when you bought it - pay the $40 to see what's going on with it. The report will tell you if the car was returned as a lemon, in an accident and where it was hit - only if insurance paid out a claim; but a good mechanic should be able to point that out - once they are under the car. The power-train warranty is 5 years or 60K miles - you seem to be one year out of warranty.

The $165 diagnostic fee is usually reserved for cars that are towed in. If you drove it in; they shouldn't have charged you that. That leaves $300 and change, that's a hour labor and $150 for the battery. They should've waved the labor charge or the diagnostic fee. If you had other services performed there, a battery check is on the basic incoming check list form - I don't know how they could've missed that. You need to sit down and read whatever warranty the dealership gave you when you drove it off the lot. IMHO, I would RUN away from this dealership.

$927 is way too much for a spark plug and coil replacement; a fair price would be <$300 - this includes the high dealer markup in parts and labor. Even a mechanic that has to look up how to change a spark plug & coil on Youtube could get it done in less than an hour. Any garage can do this job. Use this, if you think an estimate is too high Free Car Repair Estimate - Get Auto Repair Costs | RepairPal

Hope this helps...

 

Swap the coils between 2 and 3. If the problem moves buy a coil. If not buy a spark plug for #2. If necessary buy a low cost obd2 bluetooth interface to read the codes.

https://bit.ly/ObdTwo

 

A P0302 dtc alone is not usually a big deal breaker.
a leak even an OK leak, shaking at any speed and a P0302 with Check Engine Light on, is.

 

please post a copy of the certified pre owned warranty here, and we will help you decipher it

 

The dealership is not doing you any favours.

^ This is much more sensible. If you can DIY a coil swap, it'll cost you nothing.

For example, if you swap cylinder 2 coil with 4, and the code changes to p0304, then the problem is indeed the coil. But if the code stays as p0302, then the coil is not the problem,

Then try swapping cylinder 2 and 4 spark plugs, similarly. Again, if the code stays as p0302, the plug is not the problem.

Which unfortunately makes head gasket the next suspect. But start with the easy stuff.