lutter94
Well-Known Member
The ECM doesn't know anything about the cats. No downstream sensors. Throw in an off road pipe, f'd up cats could be your problem too. I had a bad o2 sensor once and it did not throw a CEL.
How hard is it replace the timing chain? I've never done one or had to get TDCDepending on the number of miles, You might think about replaceing the timing chain too,