Q: Jeep won't start, have a p0523 code

Diagnostic trouble code P0523 signifies that there is trouble with the oil pressure sensor circuit or an actual excursion, to the high side, in oil pressure. A "high" reading is being recorded by the PCM due to either electrical or mechanical faults. Check to be sure that no other diagnostic trouble codes were set because typically this Code P0523 will not explain a failure to start excepting an unusual circumstance where the problem is not an electrical fault with the circuit or switch but rather an actual mechanical problem such as high oil pressure due to an obstruction in the oil passageway, one so severe the engine is damaged. If no other codes are present, an attempt is made to determine whether the code set due to the wrong engine oil being used, a faulty connection or faulty wiring in the oil pressure sender circuit, a faulty sensor, and/or a failure to change the oil at regular intervals. If the problem is not found in these latter potential faults, obviously it is not possible to verify actual oil pressure (i.e., see if it is really high perhaps due to a blockage), without getting the engine running. Assuming the engine is not seized and that it turns "freely", the mechanic will perform a no start diagnostic (testing ignition, fuel and air induction) and get the car running. Once running oil pressure is then checked using an external gauge. If pressure is high, there could be a restriction and the resolution of that often requires engine disassembly. But, first things first, request a no start diagnostic, the Code will be addressed during that, hopefully resolved as an electrical (not mechanical) problem and then the mechanic will just simply get your car running in the course of the no start diagnostic. Please let us know if you have additional concerns or questions and look forward to helping you.