2010 Toyota Corolla LE P0171 Code… Anyone have ideas?

Hey everyone!

I own a 2010 Corolla LE and I’ve had it for about 2.5 years now. It’s got around 186-187k miles on it. So, back in August, I started noticing the VCS off light and the check engine light would come on, but the light wouldn’t stay for more than a week at a time. Fast forward to now…

I replaced the battery, MAF sensor, and spark plugs, but I’m still getting the same P0171 code. From what I’ve read, it might be the O2 sensor in bank 1, but I’m not totally sure. I’ve also attached a video of what happens after I drive for about an hour or so and then turn the car off. If I try to start it again an hour later, it does what you see in the video. Any thoughts or suggestions would be much appreciated!

Did you use an OEM MAF? They don’t go bad that often, so I’d guess it’s not the MAF. What does the freeze frame data say? Also, what RPM is it setting the P0171 code? You might want to check for any vacuum leaks and measure the fuel pressure, especially with the high mileage. A failing fuel pump could also be the issue.

Does it rattle when you start the car, either cold or warm?

Charlotte said:
Does it rattle when you start the car, either cold or warm?

Yes, it does rattle on both cold and warm starts. I think it might be related to the catalytic converter.

I had a similar issue that drove me crazy. It turned out I had low fuel pressure, so I replaced the fuel pump. It ran fine for about 3 months, but then the issue came back. Eventually, I had to replace the injectors too, as the fuel wasn’t getting through properly. It ran okay but wasn’t enough for the ECM to clear the code.