ECU : PO420 = Catalyst Efficiency Below Threshhold. From bank #1
 

Hey guys........I just updated my car with a new timing belt, water pump, plugs, wires, and dist., now afterwards I get the trouble code 420. No codes before my updates. The car runs stronger then ever but when I reset the code within a day of so the code comes back on. I have a 1996 Accord EX with 125k, 2.2 Vtec.

If my cat. is bad will that affect anything else, ie. gas mileage, motor? Or can I just drive it with no effects besides the engine light being on for code 420?

I live in Il. and no smog testing or any issue like that.

If I should replace it, does everyone buy a used one from the salvage yard or are there new ones that are affordable.

Thanks in advance for your answers.....:):)

Anthony

Re: ECU : PO420 = Catalyst Efficiency Below Threshhold. From bank #1
 

i believe when the CEL comes on the ecu has a safety feature and make the car run rich ... which will effect performance and gas mileage ... oem cat. cost an arm and a leg ... and an eye lol ... if you can find one at the junk yard that works and can get it for cheap i'd try that first ...

Re: ECU : PO420 = Catalyst Efficiency Below Threshhold. From bank #1
 

I get the same code on my 97 running an h22 with no cat. I just starting getting this code not to long ago and the car hasn't had a cat since 2001.

but yeah my car is running like crap when the code comes on.

My fix, OBD1 conversion. not a solution for you though. Sorry cant help besides you getting a cat.