2015 1.8L rattling at low rpm, head gasket?

You need to stop running it while it's rattling All that's going to do is create you cracking the girdle down below the exhaust manifold and then the engine's toast so don't run it rattling park it stop it or something. If you're going to try and save it you can pull the spark plugs early in the morning and see the water droplets on the offending cylinders generally but don't drive it or let it run rattling if you can force clear it up by stepping on the gas you can let it run a little bit while force charging the hybrid battery every so often while you figure out what you're going to do but I wouldn't be driving it rattling and all that it'll just ruin what you have and dictate a complete engine change.

 

How long have you had it?

Hang onto the old ones...

With your miles and symptoms, I'd go straight to head gasket assessment. EGR cleaning is always worthwhile, but head gasket should be first priority.

That's probably the one that tests for exhaust gas in coolant. At least at the beginning of head gasket failure, it's been coolant leaking into combustion chamber. For a DYI'r boroscope inspection the combustion chambers will likely better. Look for one cylinder (typically starts cylinder one, which is to your left stand at front) that's got exceptionally clean cylinder top, and/or pooling coolant atop piston.