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
Answer: 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 bad 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 bellhousing.
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.
Answer: 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.
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