98 Toyota Camry - Catalyic Converter, CA Emissions System

[CarStudent]

Hello everyone! Newbie here from Seattle. I have a 1998 Toyota Camry, 4 cylinder, with a check engine light on. One mechanic said that he's really sure it's the catalytic converter (cc) that needs to be replaced. It's o.k. for now, but I will need to get this done in order to pass the city's smog test for yearly registration. He gave me, however, a very expensive price for the part itself; the labor less, not such a big job. The part is supposedly very expensive because the car (dum dee dum) has a California emissions system.

I do plan to get another opinion, starting with a free code test at one of the auto parts stores, but I have some questions ..

I have been looking around google and ebay at a number of these parts - i.e. specifically for my vehicle and compatible with the California emissions system. They are selling for much less than the price I was given. So, I would like to get one of these if they're o.k. However, they come in very different shapes and sizes. Does anyone know why this would be the case? Also, some of the sellers write that their cc is compatible with the California Emissions System, but not legal in CA or NY. Of course, we are in WA state with this (pain in the neck California system ) so I am guessing we have a little more leeway in what parts we can use to replace the one that seems to be no longer working? The question, though, is, which one? And .. I'm kind of wondering if anyone knows where it is located on the vehicle? Is it hard to change yourself?

Thanks in advance for any suggestions or information!

I look forward to the forum discussions here.

[Crvett69]

did he give you the code numbers your car shows? if not when you take it in see of you can write them down. as for the cat it is usually bolted on to the bottom of the exhaust manifold or not far from it in the pipe

[Brian R.]

The HO2 sensor located downstream from the Cat. Convertor is what monitors the Cat. Convertor function. Most often, it is the HO2 sensor which needs to be replaced, not the Cat. Convertor.

Bring your VIN number to a Toyota parts department and get the Toyota part number for the sensor you need (Bank 1, Sensor 2). Then go to the DENSO website and get the corresponding DENSO part number by cross-referencing to the Toyota part number. Then go to Amazon.com and buy the sensor, using the DENSO part number as the search criterion.

[CarStudent]

Thanks for the replies, all. Oxygen sensors don't look like they cost much. How much does it generally run to have it replaced by a mechanic? Can you do it pretty easily yourself?

Since posting, I took the car to a parts store and he ran the code on the check engine light. It was the same code I had earlier from the mechanic, P0420, "the catalyst system efficiency is below efficiency."

The man at the auto parts store, however, said the same thing - it could be the oxygen sensor, instead. He said that there are two different devices to check and know for sure - one for the catalytic converter - i.e. a "heat gun" (he said you test when the car's been running, pointing it towards the area where the cc is, and if it's too cold, that's no good) - and he said there's another plug-in type device just for the oxygen sensor, similar to the device that provides the code on the check engine light.

[Brian R.]

In general, the sensor behind the cat convertor is difficult to remove from rusting and you need a torch. I would have a mechanic do the job unless you are handy with a torch.

I don't believe that the test for the cat convertor is conclusive. Just have the sensor replaced.

[CarStudent]

Thank you again for the advice. I found another mechanic and he replaced the downstream 02 sensor. Which I understand is this one shown in the youtube below, under the car seat of a 99 Toyota Camry: http://youtu.be/cs4Mn3UiDk0 The check engine light is now out and the car is running better. If the light comes back on, I am planning to have the CC replaced, though I am understanding I won't have to replace the 02 sensor again (since it was just replaced). Does that all sound correct? Also, does anyone know how much mileage you'd put on the car before the light would go on again - if it is, indeed, the catalytic converter? And how long (ballpark estimate) would a person be driving with a bad downstream 02 sensor before it ruins the catalytic converter in this type of vehicle? Hope everyone had a great 4th of July!

[Brian R.]

The P0420 code uses two-trip detection logic. After two driving cycles, the code will appear if this code is going to be triggered.

Yes, what you said is correct.

The O2 sensor will not harm your cat convertor if it is not functioning properly. It will only show if the cat convertor is functioning correctly or not (if the O2 sensor is functioning properly). If the O2 sensor is not operating correctly, it's output is meaningless and the ECM shows that as a P0420 code. A bad cat convertor will also show a P0420 code, but the O2 sensor is what normally dies, not the cat convertor.

[CarStudent]

Thanks! The check engine light still hasn't come back on; it was reset at the time the 02 sensor was replaced. Does you know how much driving around a city, or down a freeway, would be roughly equivalent to two driving cycles?

[Brian R.]

Two engine starts - followed each time by turning off the ignition

[CarStudent]

I guess that settles the catalytic converter issue, then, since I've gone through many cycles since the 02 sensor was replaced. That's a relief .. you must be the resident car angel!

I know this is off-topic, so I can ask it on another thread, if you prefer .. but any chance you have an opinion on these "dye tests" for a minor leak I have? It's 2-3 small drops per night when I leave a plastic sheet under the vehicle. It's thin black fluid in two places towards the front seat area of the car - towards the middle, and on the passenger side, closer to the door. The valve gasket cover was just replaced .. there was quite an oil mess from that, and since then, one spot does appear to be a leak, possibly a main seal, I am told. I recently had the oil changed, and I'm not seeing a noticeable decrease in the dipstick - where the oil is clean-looking - - the clean, amber color. I also heard about steam cleaning, but I guess it's not worth it to possibly end up doing both, and when one spot does look like a leak.

[Brian R.]

You can put a small amount of fluorescent dye in the engine oil, power steering reservoir, or transmission and use a black light to help find a leak. Works great if the leak isn't too bad.

Your engine is known to be a leaker. The first thing I'd try would be to check the fender under the power steering reservoir for power steering fluid (ATF). Then replace the clamps on the hoses attached to the power steering reservoir if there is evidence of a leak. Cheap fix if this is the problem. You may also have a leak in the PS high pressure line or one of its connections. Try torquing down the fittings on the PS high pressure line.

If the leak is from a main seal, it is not worth the money (IMO) to get it fixed unless you are loosing a lot of oil. One thing you can do is reduce the pressure in the engine oil sump by keeping the PCV valve clean and free-flowing. It is the only way blow-by can get out of the sump. Your engine is also known for creating a lot of blow-by (bad compression seal) which pressurizes the sump. If you've ever run your engine with the oil filler cap off, you will have seen what I mean. Not a pretty sight.

Over all, keep an eye on your engine oil and power steering reservoir levels.

[CarStudent]

Thanks again for all this great advice.

I haven't finished working with the leak analysis, yet.

But, the check engine light is "On" again, and after a little over 550 miles of mostly city driving, some freeway. Any further ideas, considering how long it's been on the road after the downstream 02 sensor was replaced?

I just took it to the auto parts store for another trouble code, and it's the same one .. p0420. This time, the store gave me a print-out of all the possibilities under this code and for my vehicle. It includes:

Possible Causes -

Catalytic converter has failed (check for physical damage and discoloration)
Check for air leaks in the Air Induction system (e.g., in the intake manifold)
Check for air leaks in the exhaust manifold and in the exhaust pipes
Front H)2S is older (aged) than the rear HO2S (HO2S is lazy)
Front HO2S or rear HO2S is contaminated with fuel or moisture
Front HO2S or the rear HO2S is loose in its mounting hole

Reported Fixes:

Replaced Catalytic Converter(s)
Replaced Front Oxygen (O2 Sensor)
Performed Catalytic Converter Burn-off Procedure
Replaced Air Fuel-Ratio (AFR) Sensor
Replaced Engine Control Module (ECM)
Replaced Manifold/Catalytic Converter
Replaced Front Catalytic Converter
Replaced Heated Oxygen Sensor (HO2S Bank 1 Sensor 1 (B1S1)
Replaced Heated Oxygen Sensor (HO2S) Bank 1 Sensor 2 (B1S2)
Replaced Oxygen (02) Sensor(s)
Cleaned Catalytic Converter(s)
Cleared Catalytic Converter(s)
Installed Catalytic Converter(s)
Performed Emission Monitor Drive Cycle(s)
Performed Fuel System Service w/P1130
Repaired Heated Oxygen Sensory (HO2S Wiring
Replaced Downstream Catalytic Converter
Replaced Downstream Oxygen (02) Sensor
Replaced Engine Coolant Temperature (ECT) Sensor
Replaced Exhaust Gas Recirculation (EGR) Vacuum Switching Valve (VSV)
Replaced Manifold Absolute Pressure (MAP) Sensor Vacuum Supply Hose
Replaced Spark Plug Wire(s)
Replaced Spare Plug(s)

So that's what I got on this sheet verbatim (give or take my typos) from the free code test at the parts store. Whew! I've also heard of people getting rid of this light by changing their gas caps, but I don't think that falls under this code.

At this point, do you think I should go get the catalytic converter changed? And considering the number of miles it's been running since the 02 downstream was replaced? Or something else?

Thanks again! Hope to also touch base again about the small leak, as well.

[Brian R.]

Do a good job of checking for leaks in the intake and exhaust system. Then replace the A/F ratio sensor before the CatConvertor. The CatConvertor would be the last resort, being the most expensive.

[Brian R.]

I believe a Toyota dealer can actually test the cat convertor.

[Brian R.]

Here is an interesting video by an expert on cat convertors:

http://workshop.search-autoparts.com...html?cid=95876