O2 low voltage?

[oscar2]

Any idea what would be causing a low voltage reading on my O2 sensor?
I've already replaced it, but occasionally the SES light still comes on and the code always shows low voltage. Sometimes the engine runs well other times, not so well. It seems to be an air/fuel misture problem but I can't figure out what is causing it?

[BNaylor]

Originally Posted by oscar2

Any idea what would be causing a low voltage reading on my O2 sensor?
I've already replaced it, but occasionally the SES light still comes on and the code always shows low voltage. Sometimes the engine runs well other times, not so well. It seems to be an air/fuel misture problem but I can't figure out what is causing it?

What year, model, and engine size? Are you referring to the 02 sensor before the CAT convertor?

[oscar2]

Sorry, I guess I should have been more specific. 2000 Alero 3.4L V6. The code scanners always show the first O2 sensor, just after the exhaust manifold. I'v changed just about everything I can think of and it still doesn't run right.

[BNaylor]

Originally Posted by oscar2

Sorry, I guess I should have been more specific. 2000 Alero 3.4L V6. The code scanners always show the first O2 sensor, just after the exhaust manifold. I'v changed just about everything I can think of and it still doesn't run right.

What was the specific odb-ii DTC error code?

The PCM receives 2 inputs from the front 02 sensor:

H02S1 Hi In
H02S1 Low In

Check the wiring at the electrical connector to the 02 sensor and at the PCM. Until the problem is corrected you will continue to have driveability problems.

[oscar2]

Sorry for the slow response, I've had other problems lately. I saw the code scanner and it only said "low volt" it didn't say in or out or what the actual voltage was. I really don't think there is a problem with the O2 sensor though, I think something else is causing a bad air/fuel mixture. I just can't figure out what. I've changed just about everything except the EGR valve, I'm not sure if that wil help, but that's my next parts change!

[BNaylor]

Originally Posted by oscar2

Sorry for the slow response, I've had other problems lately. I saw the code scanner and it only said "low volt" it didn't say in or out or what the actual voltage was. I really don't think there is a problem with the O2 sensor though, I think something else is causing a bad air/fuel mixture. I just can't figure out what. I've changed just about everything except the EGR valve, I'm not sure if that wil help, but that's my next parts change!

It's possible but the only info you have tangible are the DTC error codes related to the 02 sensor. The scanners do not show what the actual signal line is or voltage levels. The info I provided comes directly out of a GM service manual wiring diagram.

BTW - How old is the CAT convertor?