I recently bought a '02 accord. Has the 2.3l 4 cylinder. When I bought it, it had a PO420 cel light on. Figured no biggie, would replace cat, as I got car at great price. When I got home checked with obd2 and also had po131 code. Bought and replaced upstream O2 sensor and cleared codes. About 50 miles later po420 was back. The about 3 starts and 100miles later. Cel went off on its own. Problem is that once driving I can feel a sputter or lunging and u can see the rpm gauge moving while doing this. When idling it is smooth. Have done basic tune up (plugs, wires, distributed cap, button, oil change, and drain tranny fluid and fill). Also took off intake maniflod and egr valve and cleaned out some carbon buildup, but wasn't much. Sorry so much description, new to hondas and don't know what else it can be. Any help is appreciated!!

 

I have read several hundred threads and none that really match my problem.

 

Is p0131 (it is a zero, not letter O for searching) for the primary or secondary O2 sensor?

Try lightly hitting the catalytic converter and listen for a rattling sound from inside the converter.

 

I believe primary, I replaced the 02 sensor on exhaust manifold and code went away. Will tap on cat in morning after I get off work. Will update...

 

P0131 is for primary O2 sensor low voltage

What kind of sparkplugs did you use?

 

I used NGK. Pulled out in front of car this morning. Ooppss. So I had to get into throttle hard. Car hits rev limit at 5000 rpm in first and 4500 in all other gears. Once it hits rev limiter, it hangs out while sputtering until I let off gas pedal long enough for it to switch gears.

 

Problem is still that car rpm gauge is visibly moving about 100rpm when car is lunging forward. No cel on currently. Only other symptom is that it doesn't seem to have the power I would have thought the vtec motor would have, even though it is a 4 banger I thought the VTEC motor was supposed to have more power in the higher rpm, but I have none. I would not even think of passing.

 

Tapped on cat and it doesn't just rattle, if I kinda shake it u can hear chunks almost. Hearing that I plan on buying a new cat tomorrow. Does it matter if I use Honda oem cat (like $600) or can I use a aftermarket from autozone or o reillys . Will aftermarket affect mpg or just maybe not last as long? Thanks for help... Also on O2 sensor is buying a Denso brand okay or should I go back oem.

 

Where are you? In California you have to be careful to get CARB certified stuff.

Some aftermarket converters are little more than test-pipes. But AutoZone & Oreilleys are established stores, not like ebay where you never know what you're gonna get...?

Denso makes the O2 sensor for Honda to begin with, so that's good.

 

I live in Indiana. Going to get new cat and Denso O2 sensor tomorrow morning. Also, autozone asked what motor I had. Told the I have 2002 accord ex 2.3 L. They wanted to know if it was an A1 or A4.... How do I find this out? Thanks in advance.