I hope you'll indulge me (especially since I'm having to post this with my notebook since I can no longer get on the forum with my desktop). I've utilized the search feature both here and on other sites, but I haven't found the answer, or I'm too dumb to know it when I read it. Could be the latter. Anyway....I've chased this code involving the secondary air injection system for several years on my wife's '01 Blazer with a 4.3. I've researched quite a bit of data and know the usual culprits. I've had the pump out and apart, bench checked it and it worked fine.Checked the wiring and connectors and the solenoid seems to work. Checked the vacuum hoses, all without anything solid showing up. Never had any issues with blown fuses. In fact, the system works! At least it works when I start it and listen under the hood. The pump comes on at start-up, runs for maybe a minute and then shuts off. The TSB concerning the pump issue appears to have been complied with at some point in the past, as the pump intake hose is extended up by the top of the radiator and the solenoid is on the right side fender. If I clear the code, it might stay gone for up to 2 weeks or more. Or, it might be back in less than a week. Sometimes the code will clear itself and the trouble light will turn off....but it always comes back. I haven't replaced any associated parts yet. I'm thinking that maybe the solenoid could be sticking at times. The hoses on the checkvalves don't show any signs of overheating, but could they be sticking and not letting the pumped air through into the exhaust? I'm also wondering if maybe there's nothing wrong with the system itself,but it's related to the O2 data the computers getting. I've never had any O2 sensor codes. In fact the only code I've ever had is the P0410. Correct me if I'm wrong, but I believe it's possible for an O2 sensor to be not intirely accurate without setting a code. I do know this - Last week I cleared the code and my wife drove it. In the evenings I'd plug in the laptop a check the system readiness monitors. After a couple of days, all were completed but the secondary air injection and the cataylst monitor. After about 5, or 6 days the light was back on. The catalyst monitor test still remained uncompleted. Which O2 sensor/s does the computer use to complete this test and which ones does it use to determine if the pump is working? Could there be a correlation here?

 

No ideas, words of wisdom.....insults??