I have a catalytic converter code in a 1997 Outback limited; I was wondering whether the guaranteed to pass product was successful, as several people recommended that.  I pulled the battery cables to reset the computer with the check engine light on.

P0420 ? start by looking for an exhaust leak. Then, make sure all maintenance is up-to-date.

 

not many 'mechanic in a can' products work (there may be 2-3-4 exceptions) - just make certain you can get your money back and it won't harm anything.

Edited July 18, 20169 yr by 1 Lucky Texan

i can tell you i tried that stuff in a 1987 bmw 528e that had failed emissions and it had failed again even using the stuff u mentioned however the numbers did go down a bit. i cannot remember how much exactly as i have not had to smog that car in 6 years now as it has reached the 25 year mark.

Replace the front O2 sensor with a quality part, clear the ECU memory and go drive I down the freeway for a few minutes. Also, run through a full tank of premium top tier gas (Shell, Chevron, 76, Conoco).

 

Stay away from Arco and supermarket gas stations.

Replace the front O2 sensor with a quality part, clear the ECU memory and go drive I down the freeway for a few minutes. Also, run through a full tank of premium top tier gas (Shell, Chevron, 76, Conoco).

 

Stay away from Arco and supermarket gas stations.

 

Is this right?  I thought all the gas stations basically got the same gas from the suppliers.

 

Also is replacing the O2 sensor a solution for cat. converter code?  BTW after running the guaranteed product and some premium the cat code came back on.

 you could try an o2 sensor spacer. is it the code p0420? try a spacer there pretty cheap and might get you by for a while the spacer holds the o2 sensor away from the exhaust witch in turn will make it read slightly less than it normally does sometimes tricking the ecm to thinking everything is fine.

Gas stations start with basically the same gas. Different additives are mixed in depending on that particular brands proprietal mix, and then transported to the store.

 

P0420 has quite a few causes.

Best place to start is with a tune-up. Spark plugs and wires, PCV valve, air and fuel filters. Make sure you have no vacuum leaks, and no exhaust leaks.

An exhaust leak in-between the engine and cats will allow air into the exhaust stream and can throw off the o2 sensor readings.

Old worn spark plugs may not be igniting the AF mixture properly, and will cause a higher oxygen and higher unburned fuel content in the exhaust which will alter the operation of the cats.

 

Beyond that, O2 sensors. Using a scan tool to monitor voltage readings from the sensors will often reveal if one is reading incorrectly. If you don't have access to a scan tool, it's usually best to just replace both.

Thanks for the feedback; I'll go back to the auto parts place to make sure it is that code.  Actually fuel efficiency is not bad got nearly 400 miles on last tank of around 15 gallons.

Chances are slim if it's a p0420 that it has anything to do with the cats. (Is it a p0420?)

 

Read up on all the possible causes on this forum - much more likely to be one of those.

 

Only saw bad cats on a subaru once and that was at 365,000 miles

I passed the emissions test yesterday after having one of the few non-greedy garages in the area check it out and reset the computer and running a tank of premium through the tank. The guaranteed to pass did not help.