Cylinder Compression
WARNING: This page is about a different car, the 2009 Jeep Patriot and 2009 Jeep Compass. However, it is still accessible from the selected car via links, so may be relevant.
The PCM cannot detect uneven, low, or high engine cylinder compression. Low compression lowers O2 content in the exhaust. Leading to fuel system, oxygen sensor, or misfire detection fault.