NHTSA Complaint #11567608 — 2022 JEEP CHEROKEE

In late November 2023 I noticed my fuel economy dropping a lot, from 27-29mpg to 22-24mpg. And, soon tailpipes were accumulating a lot of soot in tailpipes and soot was coming out of end of muffler. I took to JEEP dealer in Palestine, TX. See invoice uploaded. Service advisor couldn't find any bad codes. He wrote some guesses as to source/cause of problem & suggested using more expensive, higher grade of gasoline. He said to try some catalytic converter cleaner, also. Seems, he thinks the braking system may be causing soot troubles. This soot problem will cause injector, spark plug, catalytic converter expenses in future! And, I have to spend much more for gasoline? I think main control module is defective and is missing computer code to properly detect this problem or is intentionally designed to ignore the cause of the excessive soot problem. It is not normal to have soot in a new vehicle!!! I've worked on vehicles since 1950s until US Government mandated electronics made us weekend mechanics obsolete. I've seen soot in old cars, pickups, tractors, other engines; but in a properly running newer vehicle. Maybe rings are bad in this engine. Maybe sensors need to be replaces but main control unit is designed to ignore soot producing part(s). Maybe sensors do not work properly especially in cold weather and causes a too rich gasoline mix in engine. But, dealers only obey what codes tell them. This sounds similar to the VW scandal where VW intentionally made software that could evade emissions control tests. JEEP has made soot problem disappear whereby sensors do not see soot being produced by V6 JEEP engine because main control unit software code has been written to do such: EVADE DETECTION THAT CAUSES NO ENGINE LIGHT ERROR NOTICE IN DRIVERS DISPLAY AND NOTHING IN DEALERS INSPECTION/DIAGNOSIS SOFTWARE. HEAVY SOOT NOT DETECTED BY JEEP's ENGINE SENSORS AND MAIN CONTROL UNIT? In person can see more soot, photos don't show 3D depth as it really is.