[JLBinHSV]

Engine (2001 xterra SE 3.3l v6) is starting to throw a 420 code every few days now, due, I think, to a cracked exhaust manifold caused by a previously leaking passenger valve cover gasket. Any serious consequences to driving the truck with this condition until I find time to replace manifold?

 

[RacerXXL]

Maybe, maybe not. The manifolds crack eventually on all the 1st Gen trucks, both of mine did, but never saw that code. Run through the diagnostic in the FSM for that code it may not be the manifold causing t5he problem.

 

[JLBinHSV]

Maybe, maybe not. The manifolds crack eventually on all the 1st Gen trucks, both of mine did, but never saw that code. Run through the diagnostic in the FSM for that code it may not be the manifold causing t5he problem.

As far as I can tell, the two primary probable causes would be a fouled catalytic converter or a faulty rear O2 sensor. Given the intermittent nature of the code, I'm thinking it isn't the converter. I'm hoping it's the exhaust manifold since I know for a fact that the manifold is cracked and leaking. I'll likely replace the O2 sensors (depending on cost) anyway when I do the job. I just don't want to make matters worse in the interim!