4.0 OHV identifying california emissions and advice on high idle/lean codes

[Michael Rogge]

Was suspecting that my engine needed new o2 sensors, according to rockauto they are different for cali and fed emissions. Attached are some pictures of relevant markings. Note that I don't know if the radiator support is original, the vehicle was in a front end collision a few owners ago as far as I can tell and the support is black when the truck is green. There is a very EGR-looking device between the exhaust manifold and intake, though if it is indeed an EGR that is a stupid design to put the EGR before the MAF and air filter.

I also have codes 172 (lean bank 1), 176 (lean bank 2), 136 (not switching bank 2), & 411 (KOER low speed idle test fail), what are the most common problems to cause this?

 

[Shran]

High idle & lean codes really point to a vacuum leak in my mind.

That deal on the air snorkel is not EGR, it's basically just a little valve that allows hot air off the exhaust to get pulled into the engine in cold weather.