My 2005 mustang GT’s check engine light came on yesterday. The 2 codes were P0171 and P0174 which are lean codes for bank 1 and 2 of the engine. The only symptom was a rough idle but no stalling out. It had no problems at driving speeds, only at idle. I cleared the code with the scanner. I restarted the car/engine and within 10 seconds the light came back on with what I presume was the same codes. I drove it home an hour and shut it off
Today when I took my car to work the light was still on but no more rough idle and then when I started the car again hours later after work the light had turned off by itself.
I always thought the check engine light needed to be manually reset with a scanner or disconnecting the battery after fixing the issue which I did not do. I haven’t recently changed anything or messed with the engine what could cause this?