code 41, 91

[AREA 91]

Why am I still getting codes 41, and 91? The engine is completely rebuilt, with 300 miles on it. The CTS, o2 sensors, are all new. I don't understand why i keep getting these. The car runs great, just the damn CEL light is on. Help guys, and girls!!!

 

[uofccatz]

No HEGO switching detected sounds like some bad wiring or something. Id make sure they are plugged in good. 41 is for the rear HEGO and 91 is for the front. Maybe incorrect o2 sensors? Whered you get them and what brand?

 

[Bizzy]

Here's a few posts to read. wink

Code 41

41 & 91

More reading material

 

[sdpatt]

Both the front and rear bank oxygen sensors are reading lean. That points to a likely vacuum leak in the intake manifold, intake-to-head gaskets or vacuum hoses. Better double check your work. An easy to overlook spot is the small hose from the manifold's rear plenum to the vacuum accumulator.