So i need a new (left side) CAT and i need to find a place that has it in stock today. The dealer has it but it is extremely expensive. The problem is that my ECU is reading code p0420 and I can not get it to pass smog with the engine light on. I went to DMV today to get an extension so i could buy a cat from a board member but they wont because they changed the law in CA where now you can only have 1 permit and you got to pay 50 bux! DAMN CA and their roadblock laws.

My SMOG result readings are:

SNIFF TEST: PASS
15mph @ 1256 rpm = CO2: 14.8 O2: 0.1 HC PPM: 12 CO%: 0.08 NO PPM: 48
FUNCTIONAL CHECK: FAIL Engine light

If i get an aftermarket CAT will the ECU clear the problem or will i still get the same error?

http://shop.autopartsfair.com/includ...MgV2FycmFudHki


Eastern Catalytic Converter

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Maybe first you should diagnose the problem, especially since your test #s indicate the cat is fine.


Regarding the question you asked, you might want to read what this guy posted:

 

replaced all the 02 sensors and canister purge solinoid & valve and tighted all hoses and its been running for a half hour with no engine light. I think i fixed it!!!

Do i need to be driving the car or is it ok just to leave it there running? 30 minutes and no engine light sounds good to me. What do you guys think?

 

Letting the car sit and idle for 30 minutes doesn't prove much with respect to the codes. Many of the code diagnostic routines are only run by the PCM under actual engine load, not at idle. P0420 will only set when the vehicle speed is between 20-75 MPH. TPS has to be greater than 2%. Mass air flow must be between 15-100 g/sec.

You've got about 3 different threads going related to this topic. Did you follow upon my suggestions in the other thread:

https://www.camaroz28.com/forums/sho...d.php?t=659471

The more you scattergun the posts and threads, the more you hurt your chances of getting good help.

 

Yea i know i have too much threads going but people are replying to everything So i don't know which to use. I wont do that again lol....

Anyway, i guess it didn't fix it. THE LIGHT WENT BACK ON THIS MORNING after 12 miles!! I replaced both 02 sensors on bank 1 (before & after cat). What else could it be? The sniff test is passing fine. Could my CAT really be bad? Or is there anything else it could be? What would u guys suggest i do. Im stumped

 

Injuneer....I replaced both 02 sensors on the drivers side and I'm still getting the code. However, the code came up after 12 miles this time...before it was about 3 miles before it went on.

My emission readings are fine,

SNIFF TEST: PASS
15mph @ 1256 rpm = CO2: 14.8 O2: 0.1 HC PPM: 12 CO%: 0.08 NO PPM: 48
FUNCTIONAL CHECK: FAIL Engine light

do you think it's the CAT or could it be something else?

 

I suggested swapping the O2 sensors side to side, and if you had done that, you could have saved the money you spent on new ones. If changing the sensors did not clear the code, you may need to consider the possibility of a wiring problem, which I beleive I have also mentioned previously. After that, the cat would be the next suspect.

 

wireing problem? as in where? like the ECU?

 

Hey guys quick question to perhaps avoid all this hassel im having. I bought thd OBDII computer. Im wondering If i clear this damn p0420 code before I smog will it pass? or will the smog station know I cleared the code?

I have a free retest, when i first tested it I disconnected the battery drove 4 miles to the shop and somehow they knew I disconnected the battery. They told me i couldnt pass because the engine light test failed. WTF!

Im nervous if i go again with resetting the ECU with the ODB reader that it will just fail again and then i wasted 60 bucks

 

If you just reset and drive in, it will fail, exactly as it did when you reset and drove in before.

What part of CA are you in? Seems like you're getting raped on the price. I don't think I ever paid more than $30 in San Diego, except at a test-only center and that was around $40.

For $60 they ought to be providing a diagnosis.

 

Wiring between the PCM and O2s. PCM grounds. PCM power.

Beyond that, I'd want to get a scanner on it and see what the O2s are actually doing - if they are behaving the way they would if the cat is actually bad (in which case its probably the O2s or the O2 wiring) or if they are normal (in which case it's probably the PCM or PCM wiring.)

Just can't believe it's the cat with those low test numbers.

 

Well i replaced both o2 sensors on the driverside CAT front and back. So i know for sure it cant be the sensors. But i used BOSCH o2 sensors, i was reading on here that i should of used the GM parts. Think that would cause the problem?

And about the test numbers....that's exactly what i thought. Maybe it has something to do with an oil leak. I was under the car right now and i noticed a lot of grease down there. But I really dont see how that would cause the ECU to read p0420 though?? If it is the oil leak what could the oil have done?

Could it be my Engine Coolant Level Sensor? I know that thing is bad and needs to be replaced but i rather not replace it cause i dont care about that little light on the dash.

Oh yea im in LA. I went to one of those test only centers where they give you the 2009 stickers on the spot. I dont even have to go to the DMV. I guess thats why it was more $

Oh yea and what is the PCM?

Thanks. Im new

 

The PCM = Powertrain Control Module = the engine and transmission control computer.

After the PCM is reset, the car has to be driven for a specific number of "drive cycles" before the various diagnostic systems will show "ready".

Your low coolant light does not interface with the PCM and is not causing P0420. If the dash light bothers you, simply unplug the harness connector from the sensor. It will go out.

Oil contamination on the outside of an O2 sensor can destroy it.

 

injuneer, can you help me find the PCM? I am not sure where to look. Should i try resetting this? I wanna try that and then check the wiring around it. Also do you think, since my emissions reading are fine, that my cat is bad? Is it possible for the CAT to be bad, yet it does not throw out bad smoke? Sounds pretty unlikely to me but who knows.

 

The PCM is bolted to a bracket on the rear of the passenger side inner metal fender, under the cowl. Shoebox has a photo:

http://shbox.com/fw/fw1.jpg

But you don't need to access the PCM to "reset" it. You pull the "PCM BAT" fuse for 30 seconds (key "off"). Pulling either the positive or negative wire off the battery will also reset it, but you will need the securtiy code for your radio if it is set for security mode.

Your emissions levels for CO, HC and NOx appear to be low. But you didn't post the "pass" values for each of those, so its hard to tell how close you are to not passing. A new cat can go bad, but if it was bad, you would have high levels for those three pollutants. My feeling is you have a wiring problem, but that's just a guess.