Have a 01 Durango R/T 110xxxKm well serviced, all at once about a week ago had this happen,engine light for low catalytic efficiency i replaced the cat right away, then i noticed the oil pressure would drop after it got warmed up and stay down until hard accel or after a few hours of sitting cold and to boot after it gets warm the rear wiper/fluid and defrost stop working!! looking for some advice especially on the oil pressure so far all i did was drop the pan and everything looked spotless i had a hard time finding solid info on other sites
Thanks

 

Sounds like you have a bad CTM.

 

yea i have to agree with hydra, replace the ctm, and your cat efficiency code might have been a simple o2 sensor, if it come back replace the after cat o2 sensor, if the oil pressure stays within the center two tick marks its fine these electronic gauges arent the best and will have some error in them.