So someone I know got sugar poured in their gas tank recently (or so they said) and I decided that it might make sense to put a locking cap in my Bravada. I figured replacing the cap couldn't hurt as I am still running the original in there. So replace it, makes sure it clicks 3+ times, and then forget about it. Now, three days later I start it up and get a CEL for air injection system and P0440. On the secondary air injection system, I usually just reset it about once a month (using Torque), but the P0440 is a new one....

Could this be a bum gas cap? I searched and didn't see any comments about it....its a Stant cap that I bought at Advance. It just seems really unusual that it happened right after I put the new cap on?

 

There's a whole string of things that can cause the P0440. It's one of the more "challenging" DTC's to troubleshoot. Here is a link to the flow chart, all 4 pages of it! https://blazerforum.com/forum/diagno...plained-35145/ A faulty fuel cap is among the possibilities, so it might be worthwhile to clear the DTC's, reinstall the original fuel cap, and perform the General Motors Driving Cycle.

 

Also the old rumor of putting sugar in a gas tank will ruin a engine is just that a rumor - Sugar does not dissolve in fuel and despite the rumor does not make a gummy mess in the internals of a engine and seize it up - It however can plug the sock or the fuel filters until its all out of the system or tank is removed to dump and flush it out - A couple cups of sand would have the same affect and is cheaper

 

I read up on it after I did the post and saw on Snopes it wasn't a real issue either lol....good catch

 

So I followed this post and put the old cap on and no codes have been thrown since. Thanks Cap! Guess I had a bum fuel cap....

 

that or your model could be like the 2002 zr-2 series blazer and be very territorial and tempermental I know someone tried replacing a fuel cap to a lock cap and when they did it threw a code to the OBD until they changed the cap back to the original cap