can catalytic converter issue cause an air injection code

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Black-Out
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can catalytic converter issue cause an air injection code

Post by Black-Out » Wed Aug 29, 2018 9:22 pm

Been gone for about 4-5 months. I been sent to no less than 4 Texas wild fires, worked a gaggle of over time and to top it off my father in law became terminally ill with lung cancer and we just lost him about a week ago. I feel like I just gotta get back to something that isn't related to anything that has to do with flames or death..... that said I had a misfire crop up on my 996 not all that long ago. It turned out to be a loose connection on one of the new coil packs I installed when I replaced all 6. I had to limp the car home on 5 and it was only about 3 miles from home so I tried to coast as much as possible. Long story short, I scanned it pin pointed the cylinder, found the connector loose made sure it snapped in place, checked the others and then cleared all codes. It was cool until day 3. I got a check engine light but the car still ran normal. scanned it again and came across a p.o. 420 catalyst inefficiency code, and a p.o.491 and p.o.492 air injection code low flow or no flow. I checked the operation of the secondary air injection motor, checked the vacuum lines for restriction and holes or cracks, checked the operation and air flow cut and open states for the flow control solenoids, and checked the operation of the pneumatic flow control valve under the intake manifold. Everything works. On a cold start I hear the air injection motor run. Now I was told by a friend that he heard that the p.o.420 can cause this fault code (p.o.491/492) to pop up.........Anyone else heard of this? I can understand I may have killed what little was left of a working catalytic converter, running a high mileage misfiring engine for a few miles, but I want to know if anyone else has heard of such a thing. I can tell you before the coil pack connector worked its way loose, I had no check engine lights on at all...
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DBJoe996
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Re: can catalytic converter issue cause an air injection code

Post by DBJoe996 » Thu Aug 30, 2018 6:27 am

If you have Durametric, you should check the Bank 2 O2 sensor readings, pre and post cat. It could be that the cylinder 5 misfire caused an overrich problem that the Bank 2 cat could not handle, and it might clear up on its own. But you should still get the pre/post cat O2 sensor readings on Bank 2 to see what is going on.

Edit - I read your post wrong and thought it was cylinder 5 that had the loose connection. So best to check the O2 sensor readings on both banks pre/post cat and see what's up.
Last edited by DBJoe996 on Thu Aug 30, 2018 9:20 am, edited 1 time in total.

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32wildbilly
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Re: can catalytic converter issue cause an air injection code

Post by 32wildbilly » Thu Aug 30, 2018 6:50 am

Black-Out wrote: Wed Aug 29, 2018 9:22 pm Been gone for about 4-5 months. I been sent to no less than 4 Texas wild fires, worked a gaggle of over time and to top it off my father in law became terminally ill with lung cancer and we just lost him about a week ago. I feel like I just gotta get back to something that isn't related to anything that has to do with flames or death..... that said I had a misfire crop up on my 996 not all that long ago. It turned out to be a loose connection on one of the new coil packs I installed when I replaced all 6. I had to limp the car home on 5 and it was only about 3 miles from home so I tried to coast as much as possible. Long story short, I scanned it pin pointed the cylinder, found the connector loose made sure it snapped in place, checked the others and then cleared all codes. It was cool until day 3. I got a check engine light but the car still ran normal. scanned it again and came across a p.o. 420 catalyst inefficiency code, and a p.o.491 and p.o.492 air injection code low flow or no flow. I checked the operation of the secondary air injection motor, checked the vacuum lines for restriction and holes or cracks, checked the operation and air flow cut and open states for the flow control solenoids, and checked the operation of the pneumatic flow control valve under the intake manifold. Everything works. On a cold start I hear the air injection motor run. Now I was told by a friend that he heard that the p.o.420 can cause this fault code (p.o.491/492) to pop up.........Anyone else heard of this? I can understand I may have killed what little was left of a working catalytic converter, running a high mileage misfiring engine for a few miles, but I want to know if anyone else has heard of such a thing. I can tell you before the coil pack connector worked its way loose, I had no check engine lights on at all...
Thanks for your being involved in the fire fighting. Not everyone would/could do that, much respect for those that do. Sorry to hear about your father-in-law. I hope the family can be at peace. Welcome back.
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Re: can catalytic converter issue cause an air injection code

Post by Black-Out » Thu Aug 30, 2018 11:18 am

Thanks man, I work for the State Police Emergency Response Communications Team. We don't fight the fires, but we provide the radio comms and video down link needed to coordinate efforts between agencies when there is no infrastructure, so we kind of get called out for everything under the sun if the disaster is large enough. When we go its never for a good thing.....As for my Father in law, we were all just blind sided.....it's like he went in for one thing and then we all found out that he had Stage 4 Lung Cancer, and roughly 1-3 weeks left to live.....Terrible situation. I figure now is a good time to try and shift my focus for a little bit before all this consumes me.... If I find any information on this issue before anyone gets back to me, Ill post it here. I'm quite sure that there's no way I'm the only one who's been here with this odd ball code situation......

Thanks again for the support though, it's greatly appreciated 32wildbilly....
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Re: can catalytic converter issue cause an air injection code

Post by 5chn3ll » Thu Aug 30, 2018 11:23 am

I would think it would be the opposite - an issue with the 2AI system is resulting in the issue with the oxygen sensor/catalytic converter.

I haven't had the issue with my 996, but oddly enough, my Corvette does suffer from an issue with the air injection valve becoming stuck every couple of years. On that car, a toothbrush, some brake cleaner, and a little elbow grease make the Chevy valves work like new. Until they clog up the next time.

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Re: can catalytic converter issue cause an air injection code

Post by 32wildbilly » Thu Aug 30, 2018 2:53 pm

Black-Out wrote: Thu Aug 30, 2018 11:18 am Thanks man, I work for the State Police Emergency Response Communications Team. We don't fight the fires, but we provide the radio comms and video down link needed to coordinate efforts between agencies when there is no infrastructure, so we kind of get called out for everything under the sun if the disaster is large enough. When we go its never for a good thing.....As for my Father in law, we were all just blind sided.....it's like he went in for one thing and then we all found out that he had Stage 4 Lung Cancer, and roughly 1-3 weeks left to live.....Terrible situation. I figure now is a good time to try and shift my focus for a little bit before all this consumes me.... If I find any information on this issue before anyone gets back to me, Ill post it here. I'm quite sure that there's no way I'm the only one who's been here with this odd ball code situation......

Thanks again for the support though, it's greatly appreciated 32wildbilly....
Sorry to disagree, but you guys do fight the fire and deal with the other disasters because what you do is necessary to make it all get better. Do not minimize your part! Father-in-law...tough situation. I feel for your whole family.

Hope you find the problem with the car.
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Re: can catalytic converter issue cause an air injection code

Post by Dgi 07 » Thu Aug 30, 2018 4:08 pm

Black-Out wrote: Wed Aug 29, 2018 9:22 pm ....... I got a check engine light but the car still ran normal. scanned it again and came across a p.o. 420 catalyst inefficiency code, and a p.o.491 and p.o.492 air injection code low flow or no flow.
First, sorry about you father in law and for the loss your family is going thru.

If you killed the catalytic converter, then its very possible that you can get an air injection code.
The system takes its measurements from the O2 sensor readings. When the pump is on, it pumps air into the cats, changing the readings on the O2 sensors. If it reads no change when the pump kicked on, them it may also think there may be a problem with the air injection system.

Most cheap scan tools should be able to give you O2 sensor readings.
Last edited by Dgi 07 on Fri Aug 31, 2018 4:46 am, edited 1 time in total.
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Black-Out
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Re: can catalytic converter issue cause an air injection code

Post by Black-Out » Thu Aug 30, 2018 6:18 pm

Dgi 07 wrote: Thu Aug 30, 2018 4:08 pm
Black-Out wrote: Wed Aug 29, 2018 9:22 pm ....... I got a check engine light but the car still ran normal. scanned it again and came across a p.o. 420 catalyst inefficiency code, and a p.o.491 and p.o.492 air injection code low flow or no flow.
First, sorry about you father in law and for the lost your family is going thru.

If you killed the catalytic converter, then its very possible that you can get an air injection code.
The system takes its measurements from the O2 sensor readings. When the pump is on, it pumps air into the cats, changing the readings on the O2 sensors. If it reads no change when the pump kicked on, them it may also think there may be a problem with the air injection system.

Most cheap scan tools should be able to give you O2 sensor readings.


Ah, ok that makes more sense. I have a great scan tool, so I can read the real time actual values.... Just figured I would force activate the pump and check the lines and flow valves manually. Just trying to figure out if the most expensive part is the way out of the c.e.l. issues. Like I said before the plug came loose from the coil pack, there were no c.e.l. codes in the car. Thanks for the response guys!

Thanks for the support as well. Means a lot to me and my family.I'm literally just trying to clear my mind by working on one of my project cars and taking care of little stuff on my 911. 32wildbilly Thanks man, I hear what your saying. I am so used to the team effort in all the stuff we do, that it just feels like its another day at the office....lol. I do appreciate the support though.
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Re: can catalytic converter issue cause an air injection code

Post by Black-Out » Wed Sep 05, 2018 7:29 pm

5chn3ll wrote: Thu Aug 30, 2018 11:23 am I would think it would be the opposite - an issue with the 2AI system is resulting in the issue with the oxygen sensor/catalytic converter.

I haven't had the issue with my 996, but oddly enough, my Corvette does suffer from an issue with the air injection valve becoming stuck every couple of years. On that car, a toothbrush, some brake cleaner, and a little elbow grease make the Chevy valves work like new. Until they clog up the next time.
I wish it was that easy for the 911 ....lol I can tell you when I opened the pneumatic valve it was easy to blow through and had minimal restriction, so I'm hoping the flow path through the system isn't gonna clog anytime soon.....but you know how that goes.....
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00' Pontiac Fire Hawk Trans-Am
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Re: can catalytic converter issue cause an air injection code

Post by Black-Out » Wed Sep 05, 2018 7:31 pm

32wildbilly wrote: Thu Aug 30, 2018 2:53 pm
Black-Out wrote: Thu Aug 30, 2018 11:18 am Thanks man, I work for the State Police Emergency Response Communications Team. We don't fight the fires, but we provide the radio comms and video down link needed to coordinate efforts between agencies when there is no infrastructure, so we kind of get called out for everything under the sun if the disaster is large enough. When we go its never for a good thing.....As for my Father in law, we were all just blind sided.....it's like he went in for one thing and then we all found out that he had Stage 4 Lung Cancer, and roughly 1-3 weeks left to live.....Terrible situation. I figure now is a good time to try and shift my focus for a little bit before all this consumes me.... If I find any information on this issue before anyone gets back to me, Ill post it here. I'm quite sure that there's no way I'm the only one who's been here with this odd ball code situation......

Thanks again for the support though, it's greatly appreciated 32wildbilly....
Sorry to disagree, but you guys do fight the fire and deal with the other disasters because what you do is necessary to make it all get better. Do not minimize your part! Father-in-law...tough situation. I feel for your whole family.

Hope you find the problem with the car.


Man, you're too kind..... Thanks for the support sir-
William-
Current Ridez:
87' Dodge Conquest TSi
88' BMW 635CSi
89' Merkur XR4Ti
90' Mitsubishi 3000GT VR-4
95' BMW M3
99' BMW 328i Sedan
00' BMW 528i Sedan
00' Pontiac Fire Hawk Trans-Am
01' Audi S4 Twin Turbo
02' Porsche 911 Carrera
08' BMW 335i Coupe
10' Mercedes Benz E350 4-Matic AMG Sport

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