Mix cola and ¼ cup bbq sauce in the bottom of the Instant Pot insert. Place the trivet at the bottom.
Next, rub cajun seasoning over the ribs. Place the ribs on top of the trivet. Lock the lid into place and turn the pressure valve to sealing.
Cook on high pressure for 30 minute using the manual setting. When done cooking release the pressure using the quick release method. Place the ribs on a baking sheet and cover in the remaining bbq sauce.
Place the rib under the broiler for 5-10 for until the bbq sauce in the desired crispness. Let sit 10 minutes before cutting and serving.