My '98 Suburban, 5.7L, 4sp auto, 4wd and 176,000 miles is giving the subject code indicating "Catalyst Efficiency Below Normal (Bank 1)". It started following an episode of misfiring that was identified as code 0300 "Random/Multiple engine misfire detected". I chose to drive a couple of hundred miles with an misfiring engine rather than walk a couple of hundred miles. After replacing the distributer cap and clearing the code, the engine seemed to run normally. After a short time, the 0420 appeared. If I clear the code it will return after the driving less that 10 miles. Any idea what my problem might be?
have the same problem?
Tuesday, October 9th, 2007 AT 6:53 PM