I got gas and check engine light came on so I checked gas cap at home and found I didn’t tighten it. When I scanned my car, the codes(p0172 & p0175) didn’t seem to be gas cap related. I checked my air filter and it looked fine. Do you have any suggestions or anyone had similar issues? I have an 07 gs350 rwd.

 

clean your maf sensor

 

when I first got my car it had an aftermarket MAF sensor and clogged PCV valve causing it to run -27% rich on the long term fuel trims

 

I cleaned the maf sensor and cleared the code. I am driving out to another town tomorrow for some errands and see if the code comes back.

 

How did it go? Verdict?

 

I just had the exact same thing happen to me. Engine just started to sputter while going thru stop n go traffic. Engine idle revs starting bouncing and vibrations, I was really nervous bc I was only like 3 miles away from reaching home after my work commute. It didnt trigger the CEL at all until the next morning. It was P0101, P0172, and P0175 all together. I cleaned my MAF sensor and blew out my F-Sport Blue Air Filter to make sure it wasnt clogged. I didnt clear the code right away bc I wanted to see if cleaning those areas saw any direct improvement. It was still sputtering though, so I cleared the codes and st/lt fuel trims by unplugging the negative terminals of the battery for 15 mins. After that, did not see any codes, and I've driven about 165 miles since then.

I think its best to check the PCV Valve, the MAF sensor (you said you cleaned it so thats good), and the whole air system, including air intake tube, filter, and the IAC Valve too. I usually clean mine every 30-40k but have been neglecting my car since I started my new job. I also drive 57 miles from OC to LA every day to work, and then 57 miles back home ofc.

Does your car also burn oil? Make sure to also check oil levels.

Lastly, after youve done everything and its not working out, I saw another forum post saying it could be the gasoline in the car is bad, and in the worst case, it could be O2 sensors.

Best of luck. Still love my 3GS, will keep it till I die or she does :P.