What could be wrong

Hello, I’m Pete from the Car Genius team at RepairPal. I’m sorry you’re dealing with this concern on your Jeep Grand Cherokee. Based on the information provided with how the engine will crank over but will not start and with you already replacing the crankshaft position sensor without a resolution and since you are receiving an error message when performing diagnostics I recommend to first check and see if any fuses are blown, many of these models have a fuse called the IOD fuse that can sometimes short out and when it does it can create all of these concerns. If all of the fuses are checked and found to be o.k. then the next thing I recommend is having the vehicle tested further to help pinpoint the concern. It may be that your scan tool that is being used may not be fully compatible with your model which can cause the error message without being the main cause for the no start concern and the no start may be something like a failed fuel pump that may need to be replaced. I do recommend having this checked into further which may require special test equipment and procedures to help identify the cause. If you’d like to find a trusted, certified repair shop in your area, you can check here: https://repairpal.com/certified. If you need more advice, or have any further questions about your vehicle, we’re here to help. Just give us a call at 877-913-1554 where we will be happy to assist!