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Have a 2004 Accord 2.4l with 170k that's throwing a few codes.

First... P0420 Catalyst Efficiency Below Threshold Bank 1Second... P1009 VTC System stuck in the advanced position Last... P2646 A Rocker Arm Actuator Control System Performance Stuck Off Bank 1The check engine light is intermittent. When on the vehicle has a rough idle and has a harsh hesitation when under load after it is warm. Often times while idling a stop light the exhaust odor is stronger than usual.

Where do you suggest I start?

Have a little mechanical experience, very little and will have a little more after doing a brake job Monday! :eek:

I am confused, what am I supposed to be watching?

Is there a youtube video or something?

Going to be a hell of a show when I try to fix this mess!

Although the o2 sensor doesn't sound all that hard, but I'm not sure if it's just the sensor or the converter.

The solenoid on the other hand is going to be a challenge.

ok - not really IMO. I will trade you. I'll fix your problem you finish swapping my Auto transmission to a 5 speed.

Anyway problem 1 - why are you betting on a bad sensor and not a bad catalytic converter? A bad converter on your generation seems to be a problem that I have seen more than a few times here on the board.

Problem 2 - someone with Vtec experience will have to chime in as I do not know. I do know that I have seen a lot of posts about Vtec problems that never seem real hard to fix.

Well maybe it's more less that I hope it's the sensor and not the converter. I was hoping the symptoms might provide some help in identifying the exact issue.

Did all of the codes turn up all at once?

For starters, I would check the oil level just be sure that you are not low on oil. Vtec runs off of oil pressure.

Yes, all showed at once.

Oil level... Check.

Would a bad converter cause the harsh hesitation and strong exhaust fumes?

For the P1009 and P2646 codes, change the oil and filter if you haven't done it recently. Generally, P0420 is for the converter unless you have an exhaust leak.

And use a good quality oil filter like the OEM Honda filter or comparable.

Redbull Sea Foam seems to come highly recommended for those two codes as well. Thinking about adding some foam then changing oil in a couple of days.

I'm sure this is going to open a can of worms, but is all oil created equal? Or is there a more recommended brand over the other? Worth paying the extra for "High Mileage" oils?

Thanks for the help guys!

Yea, that is kind of a debate.

I'm only willing to tag along with what Redbull said about the filter. Use a quality oil.

It's your choice whether you want to use sea foam, there are many Hondas and other makes out there they just survive from regular maintenance and oil changes. Most shops will try an oil change first (easy, relatively cheap, and may remedy it).

Not all oils are created equal; however, most quality oils that meet or exceed certain standards are comparable. Newer oils are not the same as oils previously sold years back.

If the cost for "high mileage" oil is the same, then it doesn't hurt to use that. High mileage oils generally have more detergents, etc. For example, at Walmart, Mobil 1 high mileage synthetic is the same price or close in price to regular Mobil 1 synthetic. You don't need to use synthetic though; although I use it.

Motor Oil Grades and Service Ratings

So I changed the oil using Mobil 1 and Mobil 1 filter. Cleared the Vtec code but the P0420 Catalyst Efficiency Below Threshold Bank 1 is still kicking out. Guy at AA said that when it was hesitating that the efficiency was thrown off, but running it and letting the converter heat up a few times may clear it out.

Does this sound reasonable or should I just replace the converter?

If the car is running ok, then I would wait. Honda catalytic converters are pretty solid and really expensive. I never had any experience with aftermarket converters.

If it were my car, I would wait to see if the code clears up. There is a video on the P0420 code on YouTube by scotty klimer (sp?). He uses lacquer thinner in the gas tank to get rid of the cat. He also suggests soaking the catalytic converter in soapy water overnight. It is worth your time to watch.

You may want to search for cataclean on here. One member had some success with that.

Oh yeah, the car runs great! Best it has run in a long time, just hope it's not going to become too dependent on that high dollar oil! Hahaha

I found a bolt on replacement at AA for $150. But I'm going to run it a bit and see if I can't get it to clear.

Thanks for all your help!