[mtdjed]

This subject is regarding Catalytic Converter problems and Engine Check Lights.

My Subaru Forester had a check engine light come on with code P0420. I won't go into my delay in getting it serviced but want to pass on that it meant that my Catalytic Converter was defective. It did not affect the car drivability but perhaps affected the MPG by some amount. But if you go to sell it will adversely affect price.

Two Things:

1/ Warranty for this item is drive train or 80,000 miles. I am at 78237.
2/ Bill Bryant price for repair and replacement $1500. My price $0 because I am under 80,000.
3/Asked Subaru rep what causes failure and was told excess fuel entering catalytic converter is one cause. Common way is consumer putting too much fuel in tank. When nozzle clicks off, many fuelers nurse more fuel into tank (up to a gallon). This fuel is not used for driving but is disposed thru a vapor canister which then sends raw fuel to engine and then not burned to cat Converter where it helps fail the converter.

4/ So if you believe this, the extra fuel pumped does nothing to give you more miles per tank but may be harmful. I checked Google and found some disagreement with this, but I won the mileage race and will not squeeze extra gas into the tank.

JED

[BobnBev]

Originally Posted by mtdjed

This subject is regarding Catalytic Converter problems and Engine Check Lights.

My Subaru Forester had a check engine light come on with code P0420. I won't go into my delay in getting it serviced but want to pass on that it meant that my Catalytic Converter was defective. It did not affect the car drivability but perhaps affected the MPG by some amount. But if you go to sell it will adversely affect price.

Two Things:

1/ Warranty for this item is drive train or 80,000 miles. I am at 78237.
2/ Bill Bryant price for repair and replacement $1500. My price $0 because I am under 80,000.
3/Asked Subaru rep what causes failure and was told excess fuel entering catalytic converter is one cause. Common way is consumer putting too much fuel in tank. When nozzle clicks off, many fuelers nurse more fuel into tank (up to a gallon). This fuel is not used for driving but is disposed thru a vapor canister which then sends raw fuel to engine and then not burned to cat Converter where it helps fail the converter.

4/ So if you believe this, the extra fuel pumped does nothing to give you more miles per tank but may be harmful. I checked Google and found some disagreement with this, but I won the mileage race and will not squeeze extra gas into the tank.

JED

Very interesting, thank you for posting.

[Walter123]

That's food for thought. Gasoline when heated creates much more vapor and needs room to expand. A real problem in Florida. I learned this today thanks to your post. I'm not cheap but I try to squeeze every last drop because of the Winn Dixie gas thing. After reading up on the subject I'm pretty convinced it's a bad practice and I'll stop when the pump stops. Thanks for posting.

[villagetinker]

There have been many cautions about over filling the newer car/truck gas tanks. I have never seen this connected to the catalytic converter failure, but have seen it connected with very expensive repairs to the closed loop vapor capture systems that as I recall are NOT generally covered under warranty.

[SCCHAMBY2000@YAHOO.COM]

Most probable cause for catalytic converter failure is an engine misfire. I had been an automotive technician for 30+ years and have not heard of that being a failure UNLESS the evaporative system is broken. It would have to have a vent solenoid problem causing the canister to fill with fuel which would cause rough idle or engine misfire. It could also be from a faulty purge solenoid that would be stuck open all the time and again would be a driveability problem. Both should set codes and turn on your check engine light also.

[Topspinmo]

Who would pump in gallon or more after you get the click? I round up to 50 cent. Or even dollar. With the price per gallon of gas that's nowhere near gallon. IMO 99.99999% of the time warranty items at the end of the warranty going to be blamed on the owner lack of maintenance! especially if you didn't have pre~ventive maintenance servicing done at dealership IMO.

I always get laugh when people take their low mileage 8 year old or older in for oil change and the business (dealership or otherwise) come back with all the overdue servicing requirements that wasn't done and they are shocked with the total bill (then want to cry fraud)(not saying it don't happen, but most wouldn't know the difference due to lack of servicing requirements). If you really read your owners manual most serving is time related also not just miles. Especially on all wheel drive European cars. Not uncommon 60k or 72 month servicing to be well over $1200 dollars and that for the lower priced models as friend found out.