SES on my 1997 Pontiac Grand Am codes system
too lean (bank 1), circuit no activity detected
(bank1 sensor 2), 02 heater  circuit (bank 1 sensor
2), H025/025 insufficient switching (sensor 1 or
bank 1) Motor has been previously changed.
I need to know what these codes mean

Going by your description of the codes, and the
fact that the engine was replaced, there could be
several reasons for these codes. You could have 2
oxygen sensors, a wiring problem, or a faulty
pcm.First check all the fuses. Check the
connections on the pcm. Possibly pinched a wiring
harness during the engine swap. Check all ground
wires and make sure none are broken or not
grounded. Those grounds are on the transmission
2001 pontiac grand am.
Why does my grand am has a check engine light come on. I had
the codes pulled from a scanner at Autozone. They said it was
p0171 and i need an oxygen sensor. Do you think this right?
How do i replace it. Where exactly is it. Thank you very much.

Thank you for the tip/donation. It is possible that the oxygen
sensor is bad. First you should check for a vacuum leak. Some
common areas of vacuum leaks on that engine are the PCV
hose, evaporative system purge solenoid valve, or upper intake
manifold gaskets. A loose air intake duct can also cause this. If
there are no vacuum leaks found, then yes, it does sound like a
bad oxygen sensor.

Thanks again for tip/donation.I will send some pics of these
areas to check for vacuum leaks, and location of the oxygen
sensor this code refers to.
Pontiac Grand Am Oxygen Sensor Codes

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