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Old 12-04-2014, 04:53 PM   #1
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CEL codes

P0491 and P0492, secondary air system bank 1, secondary air system bank 2

The electric air pump runs with a durametric

The car runs great

2003 S 6 speed

The engine was recently rebuilt from the crank out and the passages to the exhaust manifold were completely cleaned

Any idea how to troubleshoot the system or which part or condition might be the likely culprit?
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Old 12-04-2014, 05:02 PM   #2
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Quote:
Originally Posted by Jamesp View Post
P0491 and P0492, secondary air system bank 1, secondary air system bank 2

The electric air pump runs with a durametric

The car runs great

2003 S 6 speed

The engine was recently rebuilt from the crank out and the passages to the exhaust manifold were completely cleaned

Any idea how to troubleshoot the system or which part or condition might be the likely culprit?
P0491 Secondary Air Injection System, Bank 1 - Insufficient Flow
P0492 Secondary Air Injection System, Bank 2 - Insufficient Flow

Possible cause of fault
- Electrical fault in power supply or line between relay and secondary air injection pump
- Secondary air injection pump relay mechanically faulty
- Mechanical fault in electrical secondary air valve
- Pneumatic secondary air valve faulty/sluggish
- Electrical fault in secondary air injection pump
- Mechanical fault in secondary air injection pump or secondary air injection pump blocked
- Vacuum system leaking
- Air hose to secondary air injection pump slipped off or constricted
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Old 12-04-2014, 05:30 PM   #3
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Originally Posted by JFP in PA View Post
P0491 Secondary Air Injection System, Bank 1 - Insufficient Flow
P0492 Secondary Air Injection System, Bank 2 - Insufficient Flow

Possible cause of fault
- Electrical fault in power supply or line between relay and secondary air injection pump
- Secondary air injection pump relay mechanically faulty
- Mechanical fault in electrical secondary air valve
- Pneumatic secondary air valve faulty/sluggish
- Electrical fault in secondary air injection pump
- Mechanical fault in secondary air injection pump or secondary air injection pump blocked
- Vacuum system leaking
- Air hose to secondary air injection pump slipped off or constricted
Thanks, I'll start running down the items not associated with the secondary air injection pump as it runs with the durametric
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Old 02-16-2015, 03:13 PM   #4
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So these CEL codes are killing me.

First, my car does not match the parts schematic which shows this:



My #3 from the diagram above has only one large hose from the SAI, I don't have a #7 or a #4.

I've replaced my version of #3 and #14 and am still throwing the code.

The check valve #2 works well and the system holds a vacuum for about 2 minutes when drawn down with a vacuum pump. It does slowly leak back to ambient but the leak is very small. Anyone have experience repairing this gem of a system? What could be causing the CEL?
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Old 02-16-2015, 03:56 PM   #5
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Have you checked the vacuum tank for leaks? Also check the little hoses that connect the tank to the system.
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Old 02-16-2015, 04:09 PM   #6
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There is a very small vacuum leak, small to the tune of taking minutes for the system to leak back up from -20 mm hg.
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Old 02-16-2015, 04:22 PM   #7
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This is what your air injection system should look like.



M96.21/22 Air Injection 00-02 M96.23/24 03-
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Old 02-16-2015, 06:02 PM   #8
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This is what your air injection system should look like.



M96.21/22 Air Injection 00-02 M96.23/24 03-
That's it! Thanks. I've replaced #15 and #18 and still have the CEL. I'm on the edge of just replacing every single piece of it, but I'm not sure that will fix the CEL!
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Old 02-16-2015, 06:31 PM   #9
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Quote:
Originally Posted by Jamesp View Post
P0491 and P0492, secondary air system bank 1, secondary air system bank 2

The electric air pump runs with a durametric

The car runs great

2003 S 6 speed

The engine was recently rebuilt from the crank out and the passages to the exhaust manifold were completely cleaned

Any idea how to troubleshoot the system or which part or condition might be the likely culprit?
You say the pump runs with a durametric but does it come on every time you start the motor when it is cold? It should run for ~90 seconds after a cold start.
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Old 02-16-2015, 06:49 PM   #10
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Another thought... Verify the hole where #22 plugs into the cross-over tube is not blocked. Make sure that the rubber collar that connects the cross-over tube to the intake runners is not too far to one side. If that rubber collar is misaligned the vacuum hole will be blocked.
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Old 02-17-2015, 02:45 AM   #11
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Thanks Jager, both good possibilities. I'll check both and get back to you. The weather in Houston is currently miserable but I should be able to get to it later in the week.
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Old 02-17-2015, 12:03 PM   #12
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Troubleshooting SAI codes is a colossal pain, I feel for you! I had SAI codes for a long time and changed a bunch of parts saying "Ah, this has to be it!". Eventually, I changed the 1st cat, which was also throwing a code, and miraculously all the codes went away. WTF.
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