2001 Xterra SE, 4x4 manual trans. 79,000 miles. About a month ago I had to replace the right exhaust manifold, which was cracked, probably related to an accident I had last year (apparently it was missed in the initial repair job). It was repaired, and things were going well for about a week after getting the car out of the shop.
The Check Engine light came on after a week; I had noticed that one of my headlights was out, and the light seemed to turn off after I replaced the halogen bulbs -- weird I know.
A couple days later the light came back on, when after driving on the freeway, I felt a thud under my floorboard on the driver's side. Engine-wise, it still seemed to be running OK, but shifting was not quite as smooth.
To make a long story short, about 2 weeks later I failed a Calif. Smog test, with CO levels that were through the roof. Also it was noted that I was running with a lean fuel: air mixture.
My repair shop tells me I need to replace the O2 sensor -- OK, fine. But he also tells me the SRT switches need to be reset because they've all been tripped off.
My question is: were the SRT switches tripped off by the replacement of the exhaust manifold, and just not reset by the tech? Or is this a separate problem? And just WTF are SRT switches?