Cali Emissions

My 2004 Tacoma V6 has California Emission. I do not live in cali, I live in NH. My Check engine light has come on recently. I found out that the cats are failing. Can I replace them with non cali cats, or do i need to replace with cali compliant?

 

Register the truck in NH and find out their rules. CA is super finicky. I have aftermarket cats on my GTO, and despite it not throwing any codes, I was repeatedly turned down for not having OEM cats.

They don't use the sniffer on cars newer than 2000 here now, so they're cracking down on the visual. My GTO used to pass the sniffer with the aftermarket cats, so the shop didn't care. They basically said "hey it passes the sniffer, so its ok." Now it's a no go.

 

Thanks for the info

 

Thanks for the info. I guess my real question is will non cali cats make the check engine light come on? Someone told me the onboard computer will have to be reprogrammed for non cali. Is this true?

 

I would say "horse-hockey" to that. All you need are functioning catalytic converters to make the ECU happy that they are doing their job.

Better yet move to Florida, no annual or otherwise emissions or safety inspections--I moved from New England (Cape Cod) 25 years ago and do not miss a damned thing--especially shoveling and scraping, and having my cars rot out from under me...

 

1st off, if you have never had a check engine light come on, then you need to worry about the cats last. They are very robust. If you have a normal running truck, then there was nothing to cause the cat to fail.

The number 1 cause of failed cat-converter is from running for a long time with a check engine light. The light on means the truck was running in open loop mode. this is the same as running with a choke on. raw fuel has been dumped into the cat for a long time and plugging the cat.

Please tell us why you think the cat is bad.

 

Not true. I had high flow cats, no codes.

 

the code it threw was Fault code: P0420 Catalyst System Efficiency

 

Thats triggered by the rear O2 sensor.

 

would replacing it solve the problem?

 

Ever easier, try disconnecting the battery for a minute. this clears the code. If it doesn't come back on, then it was just a random abnormality with the system.

 

It is possible it's a bad sensor--but it could also be a failing/failed cat. Usually the output of failing narrowband O2 sensors will slow and fall and the ECU will complain about that (P013n, P014n, P015n, P016n DTCs) well before they actually fail.

 

Yes, if the light comes on, replace that sensor 1st. Cheap and easy.

 

If the problem is the the O2 sensor then yes, if not then no--how many milers on the truck?

You could also get the tailpipe "sniffed" that will detect a failed cat in less than 30 seconds...

 

I have cleared the code, but it comes back. If i fill my tank with super unleaded gas, after 50 miles the light goes out, until the last 1/4 to 1/8 of a tank.

 

i have around 178k on the truck

 

Fuel grade will not make any difference, as you have found.

At 178k it's a toss-up, could be the sensor or the cat--if you want to throw parts at the problem and hope you get lucky then replace the O2 sensor--if you want to know what's really wrong and fix it get the tailpipe "sniffed". With no other "O2 sensor performance" DTCs as I listed above my vote is for the cat being shot...

 

If you have a IR temperature gauge, measure the pipe temperature going into the cat and coming out. If the temperature coming out is higher the cat is working. If the temperature is lower the cat may have failed.
I killed a cat once using octane booster once.

 

does it use any oil?

The following is generalization of the O2 sensor system..
There is a formula/ratio used by the PCM to calculate the efficency of the cat... this is evidenced by the CEL light going out after you drive it a while. The front O2 sensor calculates the air/fuel ratio and should cycle through the voltage range of the sensor, .1 to .9 volts hopefully mostly in the .4 to .7 volt range. A scan tool will show a saw tooth pattern. The rear sensor should show a semi flat line. What voltage that line is at and/or cycling through is used to determine just how efficiently the convertor is doing its job.

The gamble is is it worth the dollars to put a convertor on it. You can go aftermarket. They are much cheaper for a reason... they will only last a few years because there just isnt enough convertor material in them compared to a factory cat. If you are going to replace the cat anyawy and it was my truck I would experiment with cleaning the cat. I have put solvent in the fuel tank a few vehicles that were doing what yours is doing to pass smog. A 10 percent solvent to premium fuel and take it out on the freeway where I can run the motor for 50 to 100 miles kind of hard to heat the cat up and try to burn the crap off it seems to have worked the few times I have done it. The efficency code did not come back on for quite a while after the cleaning. Eventually I had to replace the cats. I put a junk yard cat on in one vehicle and that worked out OK pluse it was way cheaper that a new cat and a new 49 state cat on in the other. Both of these were Nissan's that were not really worth the price of new factory cats.

 

The cycling of the front sensors output is because the sensor cannot do more than tell the ECU if the AFR is rich or lean--that's the narrowband part.

narrowband O2 sensor output:


Because of this the ECU just uses it's output as an indication of the AFR being lean or rich--if it tells the ECU the mix is lean the ECU injects more fuel, causing the mix to go rich--the O2 sensor then reports the mix is rich and the ECU reduces fuel to make it go lean--it does this dance repeatedly to keep the average AFR around the stoichiometric point (14.7:1 for gasoline). Thus is what causes to O2 sensor output to "cycle" between 0.2 and 0.9 volts, give or take a bit.

Here's the bank 1 front O2 sensor's output from my '03 Mustang at 2k rpm, varying from 0.184 to 0.976 volts as Glamisman stated above, at a rate of 1.0 Hz:



3-way catalytic converters chemically reduce nitrogen oxide into nitrogen and oxygen, oxidize carbon monoxide to carbon dioxide, and oxidize ("burn") unburned hydrocarbons--it is this last function that allows a narrowband O2 sensor to monitor the converter's efficiency. It makes the exhaust gasses coming out of the converter "look" lean to the sensor, reducing it's output voltage (see the narrowband output graph above). The ECU expects the rear sensor's output voltage to be lower than the front sensor, and if it isn't then either the sensor is defective or the cat is bad.

Here is more than most will want to know about narrowband O2 sensors...