Q: I have code P1120 in my pcm I replaced the throttle position sensor cleared the code and it came back less than a month later

The throttle body should be inspected for binding and dirt but there are quite a few other reasons why the code ended up returning, namely: the throttle position sensor harness is open or shorted; the throttle position sensor circuit has a poor electrical connection; and, if adjustable, the throttle position sensor is not properly adjusted. PCM updates should be ruled out as well. To get an issue like this conclusively resolved, you can request a check engine light diagnostic and the responding certified mechanic will get this diagnosed for you and estimate the repair cost based on the diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.