P0133 Code help

[chriscomputers]

My Daewoo Lanos is giving me a P0133 Code. I have had a shop look at it and they said it was the upstream O2 sensor because they tested the wiring and it was good. So I changed the O2 sensor, reset the check engine light and the problem came back. I also had the exhaust checked for leaks and did a wire and plug tune up. Anyone else have any suggestions? Could a bad fuel Injector cause this? The reason I ask is because my engine is also having detonation knock every now and again but still runs smoothly. Mainly heard at idle. Otherwise the engine runs just fine with no lack in power. My emissions are due in 3 weeks so I really want to get this figured out.

[Daniel]

What engine is it?

Here is what is said about P0133 in the Lanos service manual

DTC P0133 O2 BANK 1 SENSOR 1 SLOW
RESPONSE

Does the error code appeared on its own or after some work on engine?

Is it a OEM O² sensor in place? This question because the sensor seems to need air reference through the wire to work properly. Any modification can lead to problem.

Is the engine temperature above 70°C (first mark on gauge) while driving?

Can you check voltage, ignition ON engine stopped, at sensor? Should be ~0.450V steady. Use a digital voltmeter.