honda accord error code P0420?

[Bunty]

My honda accord 98 LX 4 Cyl 2.3 L have 91000 miles on it. It is showing error code P0420, so i took it to do the engine tune up, and i changed the spark plugs and did engine flush etc, after that the light again came on, and this time mechanic asked me to change the oxygen sensor, but the light again came on, so he again replaced the new sensor with my old sensor and refunded the money for new sensor, but now he is saying something may be wrong with catalytic convertor, and only if it genuine honda, only then the code will go, otherwise the code will be there, so please give me some advice about it, and he also told me if your car is running fine i dont have to worry about it, but i want my car to be perfect, i dont like that engine light on, all the time, please give me a advice, will bad catalytic converter hurt my car.....

the mechanic replaced the front oxygen sensor

[FELECIA]

I have a 91 honda accord ex and my engine light is on all the time... we took it to the shop and apparently there was nothing wrong with it. So im not sure. Hope you get it the way u want!!!

[TechChoicePartscom]

Did they tell you if there were any other codes stored?



DTCP0420: Catalytic System Efficiency Below Threshold



NOTE: If some of the DTCs listed below are stored at the same time as DTC P0420, troubleshoot those DTCs first, then recheck for DTC P0420.



P0137, P0138: Secondary HO2S (Sensor 2)

P0141: Secondary HO2S (Sensor 2) Heater







Do the ECM/PCM Reset Procedure.

Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.

Test-drive 40 - 55 mph (64-88 kph) for approx. two minutes . Then decelerate for at least 3 seconds with the throttle completely closed. Then reduce the vehicle speed to 35 mph (56 kph) , and try to hold it until the scan tool indicates FAIL or PASS as the TWC test result. Is the test result FAIL? YES-Check the three way catalytic converter (TWC). If necessary, replace the TWC. NO-Intermittent failure, system is OK at this time.

[Ironhand]

The "P0420" DTC indicates that there is a deterioration in the FUNCTION of the Catalytic converter.

The car has 2 O2 sensors, one at the engine, and one at the rear of the cat. Which one did he change?

There are tests that we run to determine the cause of the code.

If the Cat is tested and found to within spec, then we replace the rear sensor.

Find a shop that specializes in power-train management, preferably one that is EMISSIONS savy, like a licensed test and repair Smog-Check shop.

Look for a shop that displays the ASE symbol.