[IceWater99]

I bought a 2002 Jetta 1.8t today for $800. The seller claimed all it needed was a battery and a starter. I was able to bump start it and get it home, but it smelled like it was running super rich. I hooked up the OBD-II scanner and got these codes:
P0300 - Random/Multiple Cylinder Misfire Detected
P0301 - Cylinder 1 Misfire Detected
P0302 - Cylinder 2 Misfire Detected
P1296 - Cooling System Malfunction

The car ran at a normal temperature on the 15 mile drive home, so I'm not worried about the cooling system code just yet. But I'm wondering if the bad battery is causing cylinder the misfires. I checked the battery, and it was at 11.9 Volts with the car off. It it possible the low voltage is causing the spark plugs on cylinders 1 and 2 to not work properly, causing the misfire?

 

[Matchstick_1.8T]

It’s possible the coils aren’t getting enough power. Seems just as likely that it would be a maf issue or bad fuel injectors. First thing id do is a set of plugs. The old plugs will tell you a lot.


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[JohnDoe18]

Coils are known to go bad on 1.8Ts, especially if they've never/hardly been changed. Swap them out for a pair of fresh ones and your Sparky Plug too. They can make a HUGE difference

P1296 is most likely your Coolant Temperature Sensor. I got the same code a few months back and swapped the original Black sensor to the newer OEM Green one