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I'm new so bear with me:) I have a 2001 GXE that can't pass CA smog even though the car runs great because

1) P0134 and P0154 are pending (no activity detected on both upstream O2 sensors ).

These codes are set every time right after starting the engine. If I erase the codes with the engine running and I drive for half an hour, the codes usually don't reappear. Start the car and they are back immediately. They remain pending and no new or other codes are ever added.
I have replaced the O2 sensors twice, last time with OE sensors. No change. Also, I have checked them while the car was running and the O2 sensors normally connected to the ECM. The heater wires show ground and 14V from the battery. When I disconnect these I get the expected P0135 and P0155. The signal wire is around 0.2 to 0.4 Volt but with a regular Voltmeter I can't see the rapid changes between 0.1 and 0.9 V. That is, if they take place. All of this makes me think that the O2 sensors are OK. Does the car's good behavior mean the ECM actually uses the O2 signals to adjust the fuel mix? Then why these codes?

2) MIL is ON according to OBDII reader without the actual Engine Light being on (although bulb is OK). What could cause this?

3) the CAT and EVAP monitors are always NOT READY, the rest gets READY after a couple of hours driving.

Do you guys have any idea what my problem could be?
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