Hello. I replaced my O2 sensor and the code for it went away, but the car (a 2003 Toyota Avalon) is still giving the p0171 and p0174 codes. Could it be an IAC? I noticed that the if you clear the codes then immediately go on a drive, the code doesn't return, UNTIL you are idling, wether in park or drive. I also noticed when I turned on and off the a/c or turned the steering wheel the car wanted to die for a second. On an old post on the club Lexus forum someone said their codes were caused by air intake valve on the left side of the throttle body. Now this was on a different engine on a Lexus, I'm not sure which engine, but when I looked up air intake valve it showed me results for IAC's, which would also explain why my car almost dies with any load.
Lol, posted at the same moment 😀
@gt - Great minds think alike.
I started the car to listen for vacuum leaks, the car almost didn't start, and also ran really rough at like 400 rpms, until I reved it a little and it went to about 1500 and slowly started going to regular idle. It also smelled very bad of gasoline. I just thought of this as I was typing this, but could some of my fuel injectors be leaking, flooding the engine as it sits, and the reason it smooths out after I rev it is because all the excess gas burns off?
You've been here long enough to know the answer.
Like our FAQ suggests, follow the troubleshooting here:
