3800 P0420 code again

[cacicgtp7]

Haven't had this code pop up in about 5 months, but it came back today. Low cat threshold bank 1...whatever. I have done the trick to lenghtening my rear 02 sensor, but apparently it's not helping. Car is running great from what i can tell, so i just want this code deleted altogether since it's practically worthless.

Anythoughs?

This is on a 2005 gp ps

Thanks!

Click to read more...

 

[PANDA]

Welcome, I moved this to the 3800 section.

I assume the car is bone stock? Do you have a warranty?

 

[DanJ]

I believe the dealer or GM is obligated to replace your cat if it goes before X amount of miles.

 

[10sec]

Haven't had this code pop up in about 5 months, but it came back today. Low cat threshold bank 1...whatever. I have done the trick to lenghtening my rear 02 sensor, but apparently it's not helping. Car is running great from what i can tell, so i just want this code deleted altogether since it's practically worthless.

Anythoughs?


This is on a 2005 gp ps

Thanks!

Pay for the credits and i'll delete it for you via hptuners if you want.

 

[cacicgtp7]

Pay for the credits and i'll delete it for you via hptuners if you want.

Credits? i'm confused? If i could meet up with you sometime to delete it, that would be awesome though!



Also, i've got a dhp in there, not sure what version but i figure this is what could be causing it. It seems to only pop up in cold weather, b/c i had the same problem last winter.

John

 

[cacicgtp7]

ttt

 

[Lord Tin Foilhat]

u need credits to use hptuners on a car and delete codes.. 50 dollars is what the credits cost per car

 

[bikrboy128]

well, if it is a bad cat then you have 8 years or 80k miles to get it replaced for free no matter if you are in or out of warranty. it is a law, every car company must honor this.

 

[Lord Tin Foilhat]

its not a bad cat. its in Oxygen Sensor bank 1, before the cat.

its from the extra air with headers usually, makes it think the oxygen sensor is bad

the balts throw the same code

 

[Euro]

well, if it is a bad cat then you have 8 years or 80k miles to get it replaced for free no matter if you are in or out of warranty. it is a law, every car company must honor this.

ORLY? I'm right in on that 8 year mark, but way under 80k miles....hmmmm coincidence I think my cat is actually bad.

 

[DanJ]

no. That's P1133 or something like that. in the 3800 atleast P0420 is in reference to the rear O2 sensor and is generally triggered by a malfunctioning, aftermarket, or missing cat.

 

[bikrboy128]

its not a bad cat. its in Oxygen Sensor bank 1, before the cat.

its from the extra air with headers usually, makes it think the oxygen sensor is bad

the balts throw the same code

it's cat inefficiency bank 1. there is a difference between the terms "bank one" and "sensor 1"
there is only one cat on a grand prix, and only one set of O2 sensors, therefore there is only one bank.
unless he has an exhaust leak at one of the headers there wont be any more air going across the sensor.

Catalyst System Efficiency Below Threshold (Bank 1)
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs).

 

[cacicgtp7]

well i'd love to pay someone 50 bucks to scan and tell me if i have a leak or if it's just wacked out b/c of my dhp!

Are there symptoms that would also come w/ a bad cat?

 

[bikrboy128]

it shouldnt be wacked out by your DHP, something else is up. has your exhaust system been touched lately? also, how many miles are on the car?

 

[EmersonHart13]

420 code on my GP is the rear o2 sensor. get it when you don't have a cat or have a high flow. I deleted the code for mine because of my high flow.

 

[cacicgtp7]

it shouldnt be wacked out by your DHP, something else is up. has your exhaust system been touched lately? also, how many miles are on the car?

Nope, it's a stock exhaust minus the tips (which doesn't matter)

I had this happen about 7 months ago after putting in the dhp, and did the anti-spark plug fouler trick to lengthen my O2 sensor and it hasn't popped up since then:nuts:

All of a sudden it pops back on a week ago, i deleted it, and it's back on again...

Car has about 64,000 miles on it, mostly all highway

Even if i do have a bad cat is that going effect anything? If i delete the code then it won't throw emissions right?

 

[bikrboy128]

and did the anti-spark plug fouler trick to lengthen my O2 sensor and it hasn't popped up since then:nuts:

explain this? did you lengthen the wires on the harness side or O2 sensor side?

 

[Stink Star]

explain this? did you lengthen the wires on the harness side or O2 sensor side?

no no, you mount the O2 sensor on an extension tube outside of the normal flow path of exhaust. but i dont understand why you would do this with an otherwise stock car.....

 

[M@]

no no, you mount the O2 sensor on an extension tube outside of the normal flow path of exhaust. but i dont understand why you would do this with an otherwise stock car.....

there is no reason to

that's likely the issue...

 

[cacicgtp7]

there is no reason to

that's likely the issue...

I did this after the P0420 code came on (i had it erased) and came on again 7 months ago. I posted this up at club gp at that point, and the best advice was to do that trick to get it away from the airflow, so i tried it and it had worked....until now

 

[cacicgtp7]

After doing some extensive reading i've come to this conclusion. I need someone with a scan tool to read my rear 02's while my car is on to see if it's operating correctly (which if it is, it sounds like my cat might be bad) otherwise it's just my rear 02 being a huge bitch. If that's the case then i need it deleted.


Anyone in the area that can do this???

 

[bikrboy128]

GTP Mike has a DHP power tuner that should beable to do it. he's pretty close and on this board, hit him up.

 

[cacicgtp7]

thanks birk

 

[DanJ]

I'd love to help and am close, but after the luck TonzKnockG has had writing to the PCM and bricking them i wouldn't be comfortable touching it.