P0420 Code - 2000 Camry

[AppleGirl]

I have a 2000 V6 5-Speed Manual Transmission Camry with 192000 miles on it. I haven''''t had any major mechanical problems with the car yet except for routine maintenance. My check engine light has been on for some time and had the codes checked, which indicated that I needed a new O2 sensor. I was also told that I have three sensors and when I took it to my mechanic he said it was the Sensor 1 Bank 1 that needed to replace. My check engine light went off but came on again three days later. I again took it in to get the code check and now that one came up as a P0420.

A couple of other things that I have noticed recently as well.

First, there is a slight hesitation at times that occurs when either I am at a stop - and then begin to go OR also at high speeds and I give it gas to speed up momentarily or lane changes. It''''s not extreme, but definitely noticeable.

Second, there is a loud "humming" noise that only occurs when I accelerate and is extremely noticeable when driving less then 2000 rpms. It sounds like it's coming from the right side of the car and closer to the rear. It doesn't get louder our higher in pitch - it's pretty consistent. Initially I thought it might be something mechanical (i.e. brakes, rotors) - but I just had that work done. Also - if I take my foot off the gas and the car is coasting, no humming sound. But as soon as I accelerate, the humming noise appears. I don't notice it as much when traveling on high speeds (i.e. freeway).

Third, my tachometer doesn''''t always work. For the majority of the time, it just stays at 0 and if it''''s not at 0, it "jumps" all over the place. Sometimes even if it''''s at 0 and I hit a bump in the road, it jumps around and then settles to where it should be. I did notice that when I got my 02 sensor replaced, that it seemed to be more stable - but as of recent, it''''s back to acting crazy!

So - i''''m not sure if these are distinct and separate problems or if they are all related to the same problem. I''''d really like to keep my car for a little longer, but I also recognize that 192000 miles is a lot and maybe my car is just starting to show its age.

Any help or suggestions with these problems would be greatly appreciated!

Thanks

[toyomoho]

P0420 Catalyst System Efficiency Below Threshold

The catalytic converter on the exhaust system has one 02 sensor before it and one after. By comparing output signals from both sensors the computer is able to monitor indirectly the converters performance.

The code is stating the converter performance has deteriorated. The fix is a new converter.

The issue can also be with the 02 sensors. You replaced the one that typically fails, the sensor after the converter seldom fails.

A well-equipped shop or the Toyota dealer should be to diagnose and pinpoint the problem part without guessing.

One issue is a genuine Toyota converter is very expensive, if this is the problem try to find an aftermarket replacement converter.

The speedometer is electric receiving a signal from the sender on top of the transmission differential housing. The sensor could have a problem, the wiring or a connection with the speedometer in the instrument console.

Given the mechanic may have been in the area of the sender when doing the 02-sensor replacement it might be a loose connection at the sender. This seems to be the case owning to the fact the meter will work OK after hitting a bump.

The hum may be related to the exhaust system, the muffler is in the area your describe.

The hesitation could be a number of issues such as throttle position sensor, manifold airflow sensor, spark plugs or wiring.

[toyomoho]

Any other member comments?

I sent this person over here from another site due to lack of response over there.

[Hajoca]

You pretty much covered it, from a symptom and explanation.

I find that an exhaust or muffler shop does very well in emissions diagnostics, and would see them before taking it to an independent garage or dealer.

[new echo owner]

Do you remember what codes you had before when the check engine light first came on? The humming noise you are hearing under acceleration, can you describe it a little bit more? What would you say it sounds like, an exhaust type noise or a gear type whine or ? Beside the tach, have you notice any other part of the combination meter functioning irractically?

N.E.O.

[AppleGirl]

Sorry for the delay in getting back...i've been on vacation.

Okay, so for previous codes, here was what came up:

• P0135 - o2 Sensor
• P0440 - EVAP Emission Control System Malfunction
• P0441 - EVAP Emission Control System Flag
• P0446 - EVAP Emission Control System Circuit Malfunction

Now, after the 02 sensor was replaced, none of those codes have come back - rather I now have the P0420 code.

Also, the slight hesitation that I was experiencing prior to replacing the 02 sensor came back 3-days after it was replaced. It almost seems as if the engine is bogging down. I've also noticed that if I keep the clutch somewhat engaged while i'm giving it gas, the hesitation isn't as apparent.

In regards to the noise I hear, it probably is more similar to a high pitched whine. what's weird is that when it's really cold out or if i haven't driven the car long enough to warm up, it doesn't occur. But once it's warmed up, it comes back. The whine only occurs when i'm at less than 2000rpms. Also, I'm not sure but I think the noise prior to replacing the 02 sounded as if it was more in the front of the car and now, it sounds as if it's in the rear. I think...

I hope this helps - thanks everyone for sharing your expertise!

[freestylez]

The same code came up on my 00 Camry and my car made the same loud humming noise too. At first, I replaced my cat converter with an aftermarket one, 2 months later, the same code popped up again. After, I decided to go the OEM route, Toyota cat coverter and a Toyota O2 sensor, cost A LOT! ($1000 about for parts and labor) and the problem/CEL has stopped popping up since. I would recommend you get OEM parts and not aftermarket, since there were many threads on TN about the same issue and people were having problems with aftermarket cat converters.

[camlex]

In my 97, around 285,000 i had P0420. somebody replaced 3 times differant Cat. and CEL was comming back. Finaly i found right guy,
who installed correct one and no more CEL. If i remember right he bought from o'rreaiy(Walker). i can find found model if you needs to know.
Now my car has 342,200 with same cat.
Total charge was ~$240 (Parts and welding,labor)

Thanks,

[AppleGirl]

Thanks everyone for your feedback!

Looks like I'll be replacing the CC...yea, can't wait. . So my next question is whether or not to go with an OEM or aftermarket part. I'm not really looking forward to dropping 1G on this repair...but I guess I'll have to get it done since my car is up for emissions testing in July. So I guess - here are some additional questions I have:

• What's the main difference between the two and why are so many of the aftermarket parts so finicky?
• Is there any aftermarket equivalent that will suffice.
• Does it matter that I have 5-spd instead of an auto?
• Should I have all 02 sensors replaced with Toyota OEM's? (The one that was recently replaced is an NGK)?

What other repairs/maintenance should I have done internally to the car. I figure, if I'm going to be fixing the CC - I might as well have additional preventative work done.

Thanks again everyone.

[new echo owner]

Have you try clearing the code and see if it comes back on? With some many miles on the vehicle there are other factors that may affect the operation of the Cat, leaking injector, oil contamination, etc.

Don't recall NGK being an OEM supplier for Toyota on O2 sensor, so can say how good they work with the vehicle. An out of range or wrong O2 will indeed trigger a P0420 even if the Cat itself is functioning properly.

N.E.O.