QLex300

Hi everybody

My car was doing fine until the CHECK ENGINE LIGHT came on
02 GS 300 125k miles.
Went to dealer for them to do a look over and they found this issue.

I went to an independent shop and same thing was said as dealer, but they are almost as high as the dealer but less and said if I get the cats, they will install.
I went to Meinke, and they want 850 installed with lifetime warranty.

I looked on ebay and google and a lot of different vendors/suppliers, who in your experience or feel free to share where to get the best price and quality cat from
THANKS and I APPREICATE any and all input

TrueGS300

Does your state do smog testing as a requirement for registration?

If not, order these two things:
https://www.ebay.com/itm/31322707987...Cclp%3A2047675

https://www.ebay.com/itm/25347607280...4AAOSwBJxeFD62

QLex300

Hi
Yes Jersey does...

QLex300

I APPREICIATE all your info.

Greyhame

TrueGS,

Does this approach get rid of the Check Engine Light as well?

dwoods801

They will fool it into thinking their working correctly. However any state that has a dilligent emissions testing program, is going to have the tech give everyone thing at least a visual inspection beyond the obd diagnostics input. You can fool the obd system, but any tech will spot this right away, and fail your car. New jersey is likely to be watching for this type of cheat. You can get a new manifold and catylitic converters for under$400. And be completely compliant. The installation will probably cost another$100.
Why did you take it to the dealership and an independent shop? You should try and avoid the dealership at this point in your cars life. Find a good Indy shop that knows what they are doing and are reasonable priced, and stick to them: the dealership is always expensive

QLex300

Good Morning
No,it didn't.
Thanks for the advice.

QLex300

Good morning
At that time I was looking for a good indie shop in the *(DE.,NJ,PA aera)* and even made a post about looking for one with no success.

I think I found a good shop, *(K&M)* out of Jersey, I took my car to them for the squeaky noise Monday and they found that the harmonic balancer/pulley was jacked up, loose and no groves on the pulley and stated that was major issue that if it went complelety some other issues could result from it.

So Im going to have them do the timing belt as well and replace the serp while its apart.
I will update
@dwoods801 Thanks for all your advice and insight!!!!

TrueGS300

Yes, the the o2 extenders go into the two downstream sensors and once you clear the light, it wont come back with cat codes. This is illegal of course, but can be done in non-emissions testing states as a cheap fix. The headers are good for when the cats plug and the car hardly moves, or just as a performance mod. So headers with the o2 extenders is a cheap fix to cat issues (in non-emissions situations).

Greyhame

I've done research, pricing, and youtubing, and have come up with the following code p0430 diagnostic protocol:

1. a. The light came a few miles after I replaced the stock air filter (made in USA) with an STP air filter (made in China). I'm going to go back to stock and check the connectors that I had to undo to get the STP filter in. I know this is a long shot, as there are a lot of things that happen between intake and exhaust, but the proximity in time between the replacement of the filter and the CEL is eerie.

b. Fuel Cap or fuel cap gasket replacement

2. The coolant level is low, but the oil filler cap is not muddy frothy latte (indicating that the head gasket is intact). I have read that coolant leaks can foul the catalytic converter. I don't see how if the coolant never makes it into the exhaust manifold, but I'm going to need to track down the leak anyway. So might as well.

3. Cataclean additive

3. Oxygen Sensor (is p0430 the Bank 1 upstream sensor? The one that is hardest to access?) I've seen 2 good YouTube videos on this procedure.

4. Check for leaks in the exhaust (I really would rather not, but I will if I have to)

5. Replace stock manifold assembly with aftermarket solution mentioned above

What do you guys think of this protocol? Am I missing any steps?

Thanks very much.

TrueGS300

So unless you have leaks bad enough (and it would be audible), the P0420 and P0430 codes are quite accurate in indicating bad cats. If you have no o2 sensor codes and they are reading fine, it will be cat(s) that are the issue. How you would know is watching whats called fuel trims on live data. If the readings aren't lean, there is no leak effecting the readings. You also look for the upstream sensors to "switch" voltage. The downstream should be steady, but switching on a downstream means a bad cat. P0420 is bank 1 and P0430 is bank 2. Bank 2 is the farthest back and the harder of the sensors to replace. But as I said, if there are no codes and data is fine, no reason to suspect a bad sensor. Cats go bad due to prolonged poor engine running conditions. So make sure the car is not misfiring or running abnormally lean or rich. If it is an oil burner, IE bad valve seals, or the head gasket is indeed leaking, or there is too much or too little fuel in the mix, these are all contaminants that will destroy the cats.

Greyhame

I have an Innova code reader with the "Gauge" feature, so that may allow me to read the trim level. The car has 150,000 miles on it.

TrueGS300

Ok, well if your trims are ok then you don't have an o2 sensor problem or leak before them.