Hey guys, new to the forum as of this morning. Went into panic mode last night about my gas mileage. I have a 2007 H3 and have had it since last August, 75000 miles, no issues until now. Last week my engine light came on, called onstar and they said my emissions system wasn't functioning normally.. I thought it is running good so no big deal ill get it fixed when i can. Last night I took my wife out for dinner. I drove round trip 75 ish miles. When I started I had a more than full tank of gas. Now I am sitting slightly above half a tank. Correct me if I am wrong but I think something is a little off there.. Any advice would be fantastic! Thanks in advance!

 

What code did you retrieve. P0449?
More than a full tank of gas? Do you have a second fuel tank? Possibly you meant the gauge needle was above F? If so, that doesn't mean your tank is more than full.
Possible float sticking or sending unit board is worn. Best way to find out, is to refill and calculate miles driven/gallons. GL

 

Thank you for the reply, i ran the codes last evening and got 4. P0300(general misfire), P0442, P0449, and P0455. Planning on replacing spark plugs this afternoon. What could be causing the misfire?

 

Clear codes first, then drive and rescan... P0449 is the cvvs (common issue), p0300 random misfire, p0442 & p0455 are evap leaks, could have happened when fueling with ignition on? Fuel cap not tight?. Codes are stored until someone clears them. Clear the codes, drive it at least long enough to reach operating temp, and for the computer to monitor the evap system.Then retrieve the codes again, chances are, only 1 or 2 codes will return, those are the codes you need to address. GL