P0420 2001 Toyota camry

[max]

I have a car that I’m trying to diagnose what’s wrong with it. Has P0420 code on it, ~120K miles (which is probably when o2 sensors should be replaced by now)
When I hook up my scan tool it only shows data for one o2 sensor but car has 2 sensors. One behind cat looks pretty crispy/rusty. Car runs pretty good otherwise. Once I delete code it comes back 2-3 months later. Don’t want to replace cat if I don’t have to and it might not be issue here. Should I replace rear 02 sensor first?

Topic

[Its me]

You need to find out if you have a California car. There should be a tag in the engine compartment that lets you know. Perhaps a call to the dealer with the VIN number may help.

I am unaware of what California cars may have that is different (other than wide band O2 sensors) but note in the link you sent that it said in red “not for sale or use in California; Cannot be shipped to California addresses.” so I doubt that it is the same thing….

-Karl

[max]

Called dealer to confirm this is 50 state Camry. I’ll be ordering o2 sensor, hopefully this will fix CEL issue. Other than that car runs great.

[max]

So the car still has P0420 code. I checked for exhaust leaks yesterday and found a couple around o2 sensor (front one) and big leak around downstream o2 sensor bung. I rewelded bung where it was leaking/applied jb weld. I pulled rear o2 sensor off and it was clean, I could tell original color of the metal. I’m sure this is original o2 sensor as well.

[max]

Recently I’ve acquired a Scheffield oxygen sensor tester and according to it sensor 1 bank 1 is bad (stays in lean range all the time) So I’ll replacing it and I’ll update if this solves the problem.

[max]

So today I’ve removed front o2 sensor and it turns out to be different part # that Ive ordered.
It is 89467-33020 so which would be this Denso part # 234-9010
http://www.autozone.com/autozone/parts/Denso-Oxygen-Sensor/2001-Toyota-Camry/_/N-jfiepZ9gslx?itemIdentifier=707687_0_1784_1382%2C97999
So this makes this car California compliant? Is there way I can type in VIN # somewhere and check if it is CA emissions car? I called dealer earlier and they said it was 50 state emissions compliant.
Sticker underneath hood is for V6 engine so that tells me it was previously wrecked and I can’t go off that sticker.

[Wayne]

50 includes Cali, so yeah, CA emissions compliant.

Same crapola with a friend’s 2002 nissan xterra. small cat attached to exhaust manifold, then that attaches to another cat (that isn’t actually monitored), that connects to the Y pipe… Both banks are the same way too. 3.3L V6.

Can’t remove that first cat either without yanking the exhaust manifold as it’s jammed in there along with everything else. I despise that vehicle.

Which cat did you replace? If you replaced the second one, then it’s likely you screwed yourself, only that first one is likely getting monitored depending on the downstream o2 placement. Meaning likely the cat is still your issue. Very rarely does the P0420 show up where the sensor is the problem.

Detergent and water has been used by at least one person here with success, might try that first. Chuck it in a hot mixture, move it around a bit occasionally and let it soak for a day assuming substrates are intact.

[Paul Probus]

[quote=”mitmaks” post=91291]So today I’ve removed front o2 sensor and it turns out to be different part # that Ive ordered.
It is 89467-33020 so which would be this Denso part # 234-9010
http://www.autozone.com/autozone/parts/Denso-Oxygen-Sensor/2001-Toyota-Camry/_/N-jfiepZ9gslx?itemIdentifier=707687_0_1784_1382%2C97999
So this makes this car California compliant? Is there way I can type in VIN # somewhere and check if it is CA emissions car? I called dealer earlier and they said it was 50 state emissions compliant.
Sticker underneath hood is for V6 engine so that tells me it was previously wrecked and I can’t go off that sticker.[/quote]

Yeah, I only found out my 2001 was California emission compliant when I broke down to replace the “front O2” sensor (i.e. the A/F sensor).

Does anyone know if the lower O2 sensor for a cali emission vehicle is different from the non-cali O2 sensor? At the time I changed it, I had no idea my car was Cali, and the O2 sensor connector matched the old O2 sensor connector, unlike the A/F (i.e. upper) sensor connector. But despite changing the cat (via a local repair shop) and, now, both the A/F and O2 sensor, my car is still throwing the 0420 code.

More info: I checked the upper cat with my IR thermometer and it is working, temp in is in the 600 + degree F range and the temperature on the outlet sends my thermometer into a tizzy as it goes above 1300 degrees F and then the thermometer starts giving false readings, but then my thermometer is only good to 1000 degrees F. I have not checked the lower cat with the thermometer, I plan to do that tomorrow if I can get to changing my oil.

If the Cali lower O2 sensor is different, then that may be why my current problems persist.

Thanks,
Paul

[max]

Downstream o2 sensor is same for Cali and non-cali emission car.
Did you use Denso brand 02 sensor?
What I did is I cleaned oem cat that was on the car in detergent for 2 days. I blew out any debri/water from it and I’ve reinstalled it with new Fel Pro gaskets(make sure you use correct gasket or you might have exhaust leaks) and I’ve replaced DOWNSTREAM o2 sensor with Denso sensor.
There was a LEAK around o2 sensor bung where it’s welded onto exhaust pipe. I’ve welded that leak and made sure there were no leaks. There is NO more CEL on.

[Paul Probus]

I did not get a Denso brand, Advance Auto carries Bosch and that is what I used. Not to say you are not on to something with the Denso brand, but the Bosch should match OEM specs, so I don’t see that being the problem, but I have no way to test without finding the lower O2 sensor’s connector and testing that with my multimeter. (Is this something that can be tested while it is disconnected or do I have to leave it connected to see if the readings are within range?) The only elephant in the room, so to speak, I have thought of, but have kind of dismissed is that it is possible that the lower O2 sensor was bad from the get-go, but I have been working under the assumption it is working correctly.

Also, while I am down below changing the oil and shooting the lower cat, I plan to see if the sensor can be further tightened to eliminate potential air leak around the threads. How do you test for an exhaust leaks? I can’t see using soapy water because that would boil away and I would be afraid spraying an oil, like WD40, on the joints could catch fire.

Also, in the interest of full disclosure, I found a website that indicates that there could be an issue with the throttle position sensor (TPS) or the evap system causing a P0420 code by itself, even though there *should* be other codes pointing toward the Evap system. I made the mod to the TPS per the website (i.e. removing the metal bushings to allow the TPS to be adjusted by rotating the TPS as it is mounted to the throttle body) and that has actually improved things in that I can get about 1-1/2 to 2 hours of driving, total, in before the CEL pops back on, prior to that I could get maybe an hour at most (if I don’t use my car for anything but commuting back and forth from the train station to my house, that translates to about a week to almost a week and a half before the CEL comes on). I am still mulling over if I should open up the holes in the TPS more to see if I can adjust it more, or if I should just move on to checking the Evap system. Assuming, of course, I can definitively rule that the lower cat is working, too. I kind of leaning toward just replacing the rubber hoses to the Evap system and if that doesn’t cut it going back to the lower O2 sensor and replacing it, again (and Yes, I will order a Denso to be sure, now that I know that the Bosch may not be fully OEM compliant or something).

Oh, and I forgot to add that my last oil change, I had them change the spark plugs and wires.

[EricTheCarGuy]

Honestly, I think the Denso part would work better. They do make the OE after all. I’m not aware of the modifications you’re talking about so I can’t speak for that, but the fact that the light is still on probably means it wasn’t effective.

Good luck and keep us posted.

[max]

To test for exhaust leaks I’ve used shop vac that I hooked up exhaust side of it to the muffler and duct taped it so it wouldn’t leak. Shop vac hose slipped right over muffler outlet and I just had to duct tape it. I’ve used soapy water around all the possible areas of leaks. It worked real well.

[Paul Probus]

Mit,

I think you might be on to something with the leaky bung. When I was under the car yesterday, I noticed what appears to be two cracks on either side of the lower O2 sensor that appear to follow the bung weld. I probably would not have noticed them had i not had a flashlight. The car has over 240K miles on it, might as well replace the rest of the exhaust on it. Its original past the lower cat and is probably due anyway.

Thanks for the advice on testing for exhaust leaks.

[max]

I simply turned on shop vac and it blew air through exhaust. I could tell a leak with my hand, there was so much air bypassing around 02 sensor bung. It’s probably toyota factory defect with those bungs and it’s first thing I’d check, as well as other connections.

[Author]

Replies