2006 Mustang GT Emissions Light and DTC P0340.
I recently took my 2006 Mustang GT to Pep Boys for an oil change. They also did a transmission fluid/filter change and replaced the air filter. The next morning, my Emission light was on. I took it back to Pep Boys thinking they had caused the problem. Their diagnosis showed P0340 and they said that my alternator needs to be replaced. The printout they gave me shows that the charging system has a ripple problem. It seems odd that is was fine until they worked on it. Mileage is about 65,000.
Also, I don't understand what the alternator has to do with emissions.
Anybody have any suggestions?