2005 RL shawd pending codes p0420 p0171 p0174
picked up a 2005 RL today and first time I scanned the codes it only show PENDING p0420
after test drive it show the other two codes also pending
drove the car 3.5 hours home from another state and codes were still pending none were solid codes
problem 2 car vibrates at 60 and 80mph and up hill. when cruising downhill vibration goes away
problem 3 I have a scan gauge and it worked even on 2005 Mercedes c class to reset codes but this car it doesn't clear codes for some reason.