I have an 05 Legacy manual with 190 000 km. Whenever I back the car up I get a foul smell coming into the cabin. There are no exhaust leaks, it doesn't use oil or coolant. There is no lack of power. It gets awesome gas mileage. There are no warning lights on the dash. Could it just need a catalytic converter? I've read posts elsewhere suggesting fuel/air mix problems but I would think that the fuel economy would suffer. I would replace the CC in a heartbeat if I had a reasonable chance of success.

 

Any advice will be welcome.

I doubt it's the CAT.  

You have to think, why does it only happen when I back up?

 

I'd make sure you don't have anything stuck to the driveline that may be getting on the exhaust.  Make sure all the CV joint boots are good.

I don't know if it's any help or not, but my '96 has always had this really funky smell when starting up. I don't know if backing up is related since we always back up a steep driveway after starting it so I have nothing to compare it to. It's kind of a sour chemical smell that goes away after driving a bit. It's always passed smog with flying colors.

The smell is always there. It only comes into the cabin when reversing because I back up through the exhaust that's behind the car. I can drive hundreds of km and as soon as I back up the smell gets sucked into the car.

It's probably the ethonal gas, ethanol gas has a distinct smell when burned compared to non ethanol

 

You might try a few tankfulls from a different station, sometimes different gas stations will get different amounts of ethanol blend fuel

That's a great idea. Some higher grades don't have ethanol. I'll give that a try. With the fuel prices I can afford an experiment.

 

Thank you mikaleda!