I have a 2011 2.2L HHR. I had a check engine light and went to autozone to check it out. I was given an error code P1400. We did the basics, checking the air filter and hoses. So I took it to a mechanic to check out the exhaust manifold, it was cracked so he replaced it and also showed me there was a crack in the filler tube so he welded it,telling me it would be a temporary fix. The check engine light went out and I thought everything was fine until the light came on again with the same code. Don’t have any starting issues, no lagging or sputtering. Any suggestion?

 

Welcome to the site, not much about P1400, however it is recommended to clean the throttle body and I would clean the MAF sensor also

https://www.obd-codes.com/forums/viewtopic.php?t=10457

Now for the throttle body only use the proper spray cleaner, same for the MAF use a MAF sensor save cleaner.
Do not move the throttle plate manually, it’s real easy to strip the gears in the drive motor

 

Are you saying the flex pipe is cracked? Welding that lasts about 4 minutes.

Welded the fuel filler tube?

What were you told the P1400 means?

 

Seems the exhaust manifold was cracked and replaced. I would think would give a P0171 or P0172 code
I’m not reading flexpipe.
As for the filler tube, the fuel tank filler tube, wouldn’t that give the loose gas cap code ? As the fuel storage wouldn’t pressurize.