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Codes=All O2 sensors bad????? PCM Bad

70K views 143 replies 21 participants last post by  rlenglish  
This is a frustrating situation for sure and the suggestion to repower probably gets your heart rate up even more!! Plugged cat/cats could be the answer. Back in the early days of catalytic converters there were several local GM pick-up owners that had their rigs power reduced way down while climbing a steep grade near us. This was prior to OBD systems, and it was hard to come up with a solution, but turned out their cats were broken up/plugged inside. Resulted in a foot-to-the-floor 20 mph top speed on a long 6% grade.