Mechanics stethoscope from Sears, pull the metal tip and the diaphram, use the empty hose to listen around for a leak, can you make the sound while sitting in Park at a higher RPM, or I should say the noise, we still are not sure what it is, the stethoscope will find it if it wants to be found.

 

The CAI can cause a whistling noise. I have heard of it before. But if it is the CAI making the noise, you would probably know it.

Do you still have the same problems like the car cutting out on you and the hard starting? If so, those Bosch plugs could have already fried your coil.

 

so i disconnected the neg battery cable after i put the ngk plugs in, and the light has not turned back on yet, though i have done this many times and the time it takes for the light to turn back on changes .

 

I just got a 99 honda accord lx and I'm getting the same code the P0420 what should I havent replaced anything on it what should I do first on the car?

 

I have a 99 honda accord lx and I got the code P0420 I havent done anything to the car yet what should I look at first it seems to run fine to me.

 

Which engine?? V-6 was available in LX and it's way different from the 4-cyl.

P0420 is supposed to indicate the catalytic converter isn't working as good as it should. This is measured by the 2nd O2 sensor (located in the cat, not the one in the manifold).

I've been told that by 1999 the ECU is pretty good at telling the difference between a bad cat vs. a bad O2 sensor.

But the sensor can be thrown off by an exhaust leak blowing against the outside of the sensor, or by silicon poisoning. Done any work on the carlately??

 

99% of the time the P0420 is a bad CAT (according to the one and only Chiovnidca)

 

Your car's blowing a 420? Does the exhaust smell funny? I think it's trying to tell you to relax and mellow out, dude.

 

So is the only way to fix this is to get a new CAT?

Mine has been going on lately and I took it to a friend of mine who had the computer thingiemagoo. Honda wanted to charge me 65 dollars to "check" the code when I said just "CLEAR" the code. I had a feeling it was because the top of my air filter popped off. The last time I went into Honda to get my ignition switch replaced, they cleared the codes in the computer. I remember them mentioning the CAT sensor and they had to adjust something. I am not going to pay 65 dollars each time this stupid light comes on. I cannot have the codes blinked back to me since my d4 green light never comes on anymore (it stopped coming on when I had a new starter installed). I'm seriously considering buying one of the readers.

My friend hooked up the computer and I caught a glance at the code. I should have written it down, however, that would have been logical. I'm sure it was 0420. I cannot go to the Autozone? place that is mentioned since we don't have one of those in Canada.

Will my poor little car ever get better? [&o]

 

It's not only Autozone. What kind of car-parts chains are up there? Canadian Tire? Pep Boys? Advance Auto Parts?

You can clear the code yourself. On your 1998 you go to the right-side dashboard fusebox (near door hinges). Pull fuse #13 for 20 seconds or so.

If you clear the code & let it come back, then you erase any old leftovercodes so they don't confuse you.