2014 Jeep JK temperature swinging
Hi everyone! I’m at a total loss with my 2014 Jeep Wrangler JK (3.6L) and hoping someone can point me in the right direction. It randomly started when I parked, came back out, turned it on, and the temp spiked like crazy to 238°F just idling, so I shut it down immediately. I replaced the thermostat with a genuine Mopar unit, and while it stopped overheating, it still climbs up to 228°F before dropping back down. A couple of weeks later I noticed my oil cooler was leaking, so I replaced that assembly too, but a couple of days after that, the temps are still hitting 228°F and constantly swinging back and forth even under a steady cruising load. Since then, I've put in fresh coolant, pressure tested it, and used a vacuum-fill tool to ensure zero air pockets. I've verified the water pump is spinning by checking the return flow, confirmed the cooling fan kicks on high when it gets hot (like after highway driving), and the cabin heat blows scorching hot out of all vents with zero fluctuations. I'm wondering if it could be a failing coolant temp sensor causing these abnormal swings while cruising, or maybe residual oil got into the cooling system when I changed the oil cooler—has anyone else dealt with this or have any ideas on what to check next?