WTF mystery
 

So I changed the Lower Intake Manifold gasket (and the front head gasket, the thermostat and the temp gauge sensor) a few months back and now my 2001 Alero has some frustrating problems. To wit:

1. It's throwing a P0135 code. I replaced the oxygen sensor but the code remains even after driving 100 miles. I can't get the car inspected because the Service Engine Soon light is on.

2. The cooling system is giving me trouble. The temperature goes up past the halfway point, especially after turning the car off and then starting it soon after. I bled the system and that does seem to have made a significant difference but the temperature is still creeping upwards, although not so high as before. The thing is that I do not observe the fans coming on at all. When exactly are they supposed to come on? Can anyone recommend a good video on bleeding the system? I ran the car with the radiator cap off. I opened the bleeder while squeezing the radiator hose. Perhaps I'm doing it wrong?

3. I'm wondering if the culprit might have something to do with a small gas leak I've noticed coming from the fuel rail. When I was changing the gaskets, I saw that the washer that fits inside one of the fuel rails was broken. Being pressed for time and not wanting to purchase a stupid washer from Auto Zone for $25 that they didn't even have in stock, I replaced it with a washer that_looked_like it was the same size. Now, I see (and smell) that there is a leak there. Could that be causing the problem with the oxygen sensor and (perhaps more improbably) the temperature?

1. something wrong with wiring maybe. it's also not just distance you drive to make it go away, it's the amount of times you start the car and it runs the self-test. it might be fixed.

2. fans come on at 225 or something from the factory, you should never really see them come on. temp will always creep up when starting it after you just shut it off, it's heatsoaked, no circulation, once you get going again it should drop down.

3. no, it's the heater circuit, not sensing performance

I usually clear the codes after I fix a code. If it comes up, then I start investigating why. Other than that, ION is right, it's not the distance, it's the amount of times the car does the self test, but sometimes the code has to be cleared. My Camaro had a cooling code come up, I changed the sensor, but it wasn't "fixed" until I cleared that code. The computer is just picky like that sometimes.

As far as the fans go, one fan is supposed to cut on at 215-225, the other turns on at 235ish. I forget, but it's rare to see both fans on, UNLESS you have the A/C on, in which case the fans automatically turn on.

The other thing might be that the thermostat is rated too high. I usually try to stick with 180F thermostats. I know they come with 195F from factory, but I prefer a cool running engine instead of one that's at 200F all the time.