Error code PO420
Thread Starter
Melting Slicks
Joined: Jul 2000
Posts: 2,722
Likes: 115
From: Phoenix AZ
Error code PO420
Got a check engine light today and a code PO420. Looked up the IPC Code and said TWC Low Efficiency :confused: Any help?
Another item, I posted a few days ago and got no response. My windshield washer button on the wiper arm flew out. The wipers stay on & the fluid keeps spraying. There are two springs inside the stock & the button. I can't find one of the springs. Found out I had to order an entire stock can't just get the springs. I had to pull the #10 fuse to disable the wipers. I wonder if this may be the problem with the code if it's a communication problem (TWC Twilight Sentinal maybe :confused: )
Thanks
Another item, I posted a few days ago and got no response. My windshield washer button on the wiper arm flew out. The wipers stay on & the fluid keeps spraying. There are two springs inside the stock & the button. I can't find one of the springs. Found out I had to order an entire stock can't just get the springs. I had to pull the #10 fuse to disable the wipers. I wonder if this may be the problem with the code if it's a communication problem (TWC Twilight Sentinal maybe :confused: )
Thanks
Thread Starter
Melting Slicks
Joined: Jul 2000
Posts: 2,722
Likes: 115
From: Phoenix AZ
Re: Error code PO420 (jfpilla)
The wiper parts are under warranty. The car's an '02. The dealer wanted to put the entire new stock in but I want only the springs and button. I told him to take apart the new unit and get me those pieces. I don't want them to take apart the steering column or whatever else to do this job.
If you look at the button, there are four legs, two that go inside the springs and two with a j-hook that should hold it in place. My j-hooks look like they are tipped in (warped) slightly and may not hold it in place.
The funny part is I don't think there is much tension on those springs when the button is in the off/out position. That button & springs were shot across into the passenger seat, like if you pushed it in then let go and it came apart but I never did that.
If you look at the button, there are four legs, two that go inside the springs and two with a j-hook that should hold it in place. My j-hooks look like they are tipped in (warped) slightly and may not hold it in place.
The funny part is I don't think there is much tension on those springs when the button is in the off/out position. That button & springs were shot across into the passenger seat, like if you pushed it in then let go and it came apart but I never did that.
Drifting
Joined: Dec 1999
Posts: 1,330
Likes: 36
From: Waynesboro, PA
Co-winner 2020 C4 of the Year - Modified
Re: Error code PO420 (grady)
Ooh Ooh Ooh, I know this one. I work at a dealership (not GM) and see this every day. You know the codes for all makes are the same since the whole OBDII thing. Where I work, P0420 is the code for catalyst deterioration, hence your TWC low efficiency ( Two Way Converter). Basically, your downstream (after cat) O2 sensor is not reading enough of a change in exhaust gas oxygen content from the upstream ( before cat) sensor. Either a problem with an O2 sensor or your converter is shot. Good thing this C4 guy happened to be reading your post in the C5 section! Glad to be of assistance.
Darren
Darren
Drifting
Joined: Dec 1999
Posts: 1,330
Likes: 36
From: Waynesboro, PA
Co-winner 2020 C4 of the Year - Modified
Re: Error code PO420 (grady)
By the way, are all 4 (I think) O2 sensors still in place after your exhaust work? How long after your headers and exhaust installation did the light come on?
Thread Starter
Melting Slicks
Joined: Jul 2000
Posts: 2,722
Likes: 115
From: Phoenix AZ
Re: Error code PO420 (POLOVETTE 94)
Polovette 94;
I had a '98 and had TPIS headers and B&B PRT's installed. When I traded it for the '02 the dealer swapped the entire exhaust system. I did have 48k miles on these cats and added another 2k since. I have to pass an emissions inspection. I actually did this three weeks ago and the dealer told me the car is running very clean. I was nervous about passing the test since the removal of the two pup cats that the '02 had vs. the '98 but all went well. I had an error code (can't remember which one but it was an o2 code) right after the parts swap but the dealer changed o2's to eliminate the error. I hope I didn't burn these new one's up. I'd rather it be cat problems knowing there is 50k miles on them. I don't want to keep needing new o2's
I had a '98 and had TPIS headers and B&B PRT's installed. When I traded it for the '02 the dealer swapped the entire exhaust system. I did have 48k miles on these cats and added another 2k since. I have to pass an emissions inspection. I actually did this three weeks ago and the dealer told me the car is running very clean. I was nervous about passing the test since the removal of the two pup cats that the '02 had vs. the '98 but all went well. I had an error code (can't remember which one but it was an o2 code) right after the parts swap but the dealer changed o2's to eliminate the error. I hope I didn't burn these new one's up. I'd rather it be cat problems knowing there is 50k miles on them. I don't want to keep needing new o2's
Drifting
Joined: Dec 1999
Posts: 1,330
Likes: 36
From: Waynesboro, PA
Co-winner 2020 C4 of the Year - Modified
Re: Error code PO420 (grady)
Grady,
I'm not too familiar with the converter setup on the LS1. Are you saying your new one came with 4 converters as opposed to the 98 having only 2? If this is the case, the 02 vette's computer may be looking for a cleaner exhaust gas, probably to pass some low emissions vehicle standard that the 98 model wasn't set up for. I forget the exact code for a bad O2 sensor, but the P0420 is for catalyst deterioration. In other words, the O2 sensors are working and switching fast enough, but the downstream ones aren't seeing enough (or any) of a change from what the primary ones are sniffing. This smaller difference may have been enough for the 98 PCM, but if the 02 had 4 cats, the computer is probably looking for a cleaner exhaust flow. You may have to switch back to the 2002 converters. Let me know what happens.
Darren
I'm not too familiar with the converter setup on the LS1. Are you saying your new one came with 4 converters as opposed to the 98 having only 2? If this is the case, the 02 vette's computer may be looking for a cleaner exhaust gas, probably to pass some low emissions vehicle standard that the 98 model wasn't set up for. I forget the exact code for a bad O2 sensor, but the P0420 is for catalyst deterioration. In other words, the O2 sensors are working and switching fast enough, but the downstream ones aren't seeing enough (or any) of a change from what the primary ones are sniffing. This smaller difference may have been enough for the 98 PCM, but if the 02 had 4 cats, the computer is probably looking for a cleaner exhaust flow. You may have to switch back to the 2002 converters. Let me know what happens.
Darren
