P0420 Catalyst System Efficiency Below Threshold Question

Guys, i need some help here, i went to Autozone today and they hooked their unit up to my car and got this code: System Efficiency Below Threshold(code# P0420). Can anyone suggest where i start troubleshooting my wifes car to get the engine light to go off?
its an 1998 Honda Accord LX 4 cylinder with 99,137 miles
Any info would be greatful.
Thanks
Rockey

not sure about honda's but on audi's, it's straight forward. if the fault returns more than once, replace catalytic converter. and that is the only thing we have had make that fault stop.....

Guys, i need some help here, i went to Autozone today and they hooked their unit up to my car and got this code: System Efficiency Below Threshold(code# P0420). Can anyone suggest where i start troubleshooting my wifes car to get the engine light to go off?
Any info would be greatful.
Thanks
Rockey

year model and engine would help and miles too

If by chance it's an '03 4 banger.....

A quick efficient way to improve your emissions is what we call a "Mexican tune-up" basically you just give your car a run at very high revs to clear all the gunge out of the system.. Give it a try.. it will improve things, but may not be enough to put your light out. :paranoid:
.

for '98

As James said, you can try having the code cleared. Then just floor the throttle all the way until it shifts into 4th (if auto), 5th is stick.

Repeat it several times to heat up the cat a lot.

This sometimes will keep the light off for a while. On the '98 V6, doing that kept the light off at first for up to 6 months, then it deteriorated over time to where the cat died.

It was really easy to tell too, the horrid old 60's exhaust stench coming out while the car was hot and driven for a while confirmed it. That and the matching o2 voltages from the front and monitor sensors.

There is definitely a big difference in smell between a non-cat car and one that's got a properly functioning cat.

Does your car use any oil? Also, does it have ANY exhaust leaks, anyplace in the system?

That i am aware of it does not use any oil although i have not kept a close eye on it as its my wifes car nor have i noticed any exhaust leaks.
thanks for all the info

As James said, you can try having the code cleared. Then just floor the throttle all the way until it shifts into 4th (if auto), 5th is stick.

Repeat it several times to heat up the cat a lot.

This sometimes will keep the light off for a while. On the '98 V6, doing that kept the light off at first for up to 6 months, then it deteriorated over time to where the cat died.

It was really easy to tell too, the horrid old 60's exhaust stench coming out while the car was hot and driven for a while confirmed it. That and the matching o2 voltages from the front and monitor sensors.

There is definitely a big difference in smell between a non-cat car and one that's got a properly functioning cat.

Does your car use any oil? Also, does it have ANY exhaust leaks, anyplace in the system?

To clear the code on a 1998 Accord 4 cyl. Open the front passenger door, remove the fuse panel cover on the side of the glove compartment, pull fuse # 13 and replace. You'll now have to reset your clock also.
P.S. The jumper holes are #'s 8 & 13.

Exact same problem here and exact same car, except mine is a 1998 Accord EX.
I brought the Innova code reader and it has a feature the clear the light, but I don't want to do that until I have to do a emmissions check, as that will make it difficult for the mechanic to diagnose.
I do get that stench that you guys talk about. Have been getting that for last 3-4 months, so got the Catalytic convertor heat shield replaced, as during last years Spring car clinic, that was recommended, but I postponed it. Thought that triggerred this code to come now, as I recently got the heat shield replaced.
But dealership is denying that and want $120 bucks to diagnose what all needs fixing when this code comes up.

Guys, i need some help here, i went to Autozone today and they hooked their unit up to my car and got this code: System Efficiency Below Threshold(code# P0420). Can anyone suggest where i start troubleshooting my wifes car to get the engine light to go off?
its an 1998 Honda Accord LX 4 cylinder with 99,137 miles
Any info would be greatful.
Thanks
Rockey