Subaru Repair: Decrease in fuel efficiency 97 Legacy Outback, Subaru runs rough, Subaru check engine light

Question
Hi,
I had a P301 misfire code in January.  I had the code shut off and the check engine light has not come back on but I have noticed a decrease in fuel efficiency and the car seems to be idling hard when I am at a stoplight (automatic transmission).  Any suggestions at to what could be wrong?  Thank you.

Answer
Natalie,

Clearing the code doesn't fix the car, If you are driving your Subaru around with a intermittent misfire you could be slowly damaging the catalyst amongst other things as well.

Repair the cylinder #1 misfire and it should regain some of its lost fuel economy, also when you clear the code you also clear the memory from the vehicle as well and this is why it is a real bad idea to do so. Data that was stored in the computers memory that could have been useful in detecting why the light came on in the first place is now gone. Also when the memory is dumped any learned drive patterns will be lost for the car and fuel economy will suffer as a result.  Next until all of the drive cycles are performed not all of the monitors will be back to ready status and as a result problems may go undetected until the vehicles computer monitors are all back to ready status.

Rather then clear a code, if the car is fixed the light will go off all by itself.

Justin