I have a 2002 Dodge Grand Caravan that recently dropped in fuel economy by 7 mpg with no check engine light showing. Doing a key on, the check engine light does come on so I know that it is working. I have changed the spark plugs and wires on the van to see if it would help, but has not. The van has 67000 miles on it.
I have also tried running fuel injector cleaner through the system as well as Cat-a-clean from Advanced Auto parts to see if it was a dirty O/2 Sensor or partially clogged Catalytic Converter.
This car uses a MAP sensor, and I have tried cleaning it along with spraying throttle body cleaner into the intake.
The air filter is clean and was put in the van back in May.
The issue started a couple of weeks ago after a fill up, I would have thought that the possible bad gas would have been out of the system by now since I have run the van down to almost nothing left in the fuel tank a couple of times.
I am thinking that it is a sensor possibly out of calibration, but do not know for sure since I do not have a scan tool that shows me what the van is doing actively while the van is running.
Any thoughts as to what could be the cause of the issue?