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Ok guys, now that this seems sorted out. In my case the problem was a faulty air change-over valve. Since I was at it I also changed the electric change-over valve.

I thought I'd post an entire post-mortem on the whole incident. This way future reader can get all the info in one spot. In short, no horror stories but a lot learnt. A Huge thanks to Loren, 1999Porsche911 and tholyoak for helping me thru this.

Guys, I'm going to be quoting you in the writeup below, hope you guys don't mind. If people want to read the original message and the whole thread, its below.

Background

=============

I got the P0410 ("Secondary Air Injection Malfunction") and P1411 ("Manufacturer Control Auxillary Emission Control") along with a Check Engine Light ( CEL).

What is means

===============

During a cold start the catalytic convertors don't work very efficiently because they are cold. To compensate for this there is an air pump which adds air to the exhaust gases so the cat's behaviour can be somewhat compensated for. If you get this error that additional air isin't being mixed with the exhaust gases. No vehicular damage ( CEL shouldn't be blinking!) but your emissions care higher during every cold start.

What to do next (if you plan on fixing it yourself)

================================

1) Observe the connection below

post-2-1153948546_thumb.jpg

1 - Secondary air injection pump

2 - Air change-over valve

3 - Electric change-over valve

4 - Non-return valve

5 - To the cylinder heads

6 - Vacuum reservoir

7 - To the intake air system

Basically 1 pumps the air thru 2->4->5 and reaches the exhaust gases. The computer controls when to start the blower and also when to connect the air link by controlling #3. When #3 is "ON", the vacuum line is connected to #2 which turns #2 "ON". Then #2 will connect the air blowing from one pipe thru to the other pipe. You should check every component in that chain starting from the easiest to check to the most difficult.

1. Check Air injection pump (#1, ~$430)

============================

- Do a cold start, the secondary air pump should run at least 30 sec (or more).

- Sounds like a small vacuum cleaner/touch it to feelt it hum/pull off the larger hose to feel it blow air

- If the pump "fails", here are the reasons :

A.) "Check the electrical connections and fuse (40A fuse on the relay board next to the DME), and the relay (position 10 on the same board)." - Loren.

B.) If the fuse seems ok its possible the pump is dead (you did test this with the car cold - cold start , right ?).

TIP: Before buying a new pump ($$$) you could take it to a porsche dealership and have him quickly/freely verify this for you.

If your air pump works, then you need to check #2 and #3. Both of these are deep inside the engine bay.

You MUST remove the alternator before proceeding. Please read that thread on alternator removal - you will save several hours of frustration and sore fingers if you read before you work !

Once you remove the alternator (aka generator) you should see this ... its basically the same system shown in the black/white diagram above but this is how it looks in real life.

post-8807-1156486017_thumb.jpg

NOTE-1 : Please note the existing connections on the tubes before you rip everything out. A camera/camera phone comes handy.

NOTE-2: For the steps below, make sure you DON'T let the tubes/pipes slide away into the inaccessible areas of the engine bay - they are a HUGE pain to bring back if they slip away (unlikely-but you're warned!)

NOTE-3: Finally, if you've opened the whole thing till here, I'd suggest you test both #2 and #3 to be sure you catch every failed part in that system. I simply replaced both with new parts even thought only #2 was bad in my case - #3 was just another $20 !

2. Air change-over valve (~$80)

======================

- Note existing connections

- Use nose pliers and slide the ring-clamps away from the valve onto the respective rubber hoses.

- Take the little pipe off

- Remove the valve piece out of the engine bay -> clean it with some alcohol wipe (don't drench it in any weird clearer/liquid - you're just sanitizing this for the next step).

- Wash and clean your hands (Yes!)

- Suck air out of the little pipe and quickly put your finger on it (to maintain its low pressure). If this is tough, ask your significant other (chances are they'll go "eeeeks").

- If you find you cannot maintain a low pressure on the little pipe (i.e. it feels 'open' when you suck out the air) then your valve is bad.

- This low pressure should open the valve and you should be able to blow from one pipe (coming from the air blower) thru to the other.

- If you cannot blow thru and are sure the low pressure is maintained, you again have a bad valve.

3. Check the Electric change-over valve (~$20)

=================================

These are triggered off a 12 V supply. The valve has (+) and (-) markings for polarity of the electric connector. I quickly rigged up a 12 V supply by cascading a 9V battery with 2x 1.5 v batteries, some duct tape and some wiretags/wires. If your physics is rusty, this is the connection figure.

(-A)---(-)[9 volts](+)--(-)[1.5volts](+)--(-)[1.5volts](+)--(B+)

Between (-A) and (B+) you have 12 volts !

- make a note of existing connections

- remove the valve from the engine bay

- Connect the wires coming out from A and B to the electric change over valve's connection

- If you've got a working valve, you will hear a click sound when the valve triggers.

- Now, also blow from one pipe (after wiping it with an alcohol wipe!).

- you will be able to blow thru/NOT blow thru as the valve opens/closes as you connect/disconnect the 12v supply wires.

TIP: Check #2 also and if ONLY your electric valve(#3) is faulty, you could test the "FALSE HIT - valve from another system" valve similarly. If this "FALSE HIT..." valve works, you could swap it with #3, reassemble the car and drive ! The benefit ? The "FALSE HIT..." valve is accessible without _ANY_ disassembly and you can replace it some other day under 5 minutes when your replacement valve arrives. Also, no harm if the car is driven for the time being with that valve being faulty.

Hope this helps !

Cheers!

Sid

-----<original post below> --------------------

Well, I got a CEL last night. So I stopped by Autozone and borrowed their OBD2 and got the following ...

1) P0410 : "Secondary Air Injection Malfunction"

2) P1411 : "Manufacturer Control. Auxillary Emission Control"

My car = MY99 996 C2, North America.

I saw some other posts on P0410 and today morning checked the air pump on the left side/driver side of the engine compartment near the tail lights. It seems to be working in that I could hear it buzz like a mini-vac. Not sure exactly part was making that sound, I also touched it to feel it vibrate (just like an electric motor should).

I quickly glanced to see if the rubber hose on the pumps lower-back-right end was still connected and visually it looked ok. I'll have another closer look later (was behind schedule this morning!).

Do you guys have any good pointers on what next I should do ?

FYI, I have modified my stock exhausts with a regular bypass pipe, fabricated along the lines of the PSE version2. It sounds great and there hasn't been a change in the exhaust note since then till now/ CEL coming on. I don't think its related but I thought I'd mention anything exhaust in this post.

Thanks in advance guys !

Sid

PS: I just got my customised plate .... SIDS 911 :D ... (actually SID5 911)

Edited by siddharth
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P0410 Secondary Air Injection System - Signal Implausible (Cylinders 1 - 3)

P1411 Secondary Air Injection System - Signal Implausible (Cylinders 4 - 6)

Potential causes:

Secondary air injection pump is not triggered. - Wiring harness or fuse

Secondary air injection pump does not work. - Relay

Air supply lines restricted. - DME control module

Electric change-over valve does not work. - Air supply lines

Air change-over valve does not work. - Secondary air injection pump

Vacuum system leaks. - Electric change-over valve

- Air change-over valve

Did you or someone disconnect the secondary air pump?

I would start by checking for the noise when you start the car cold - the secondary air pump should run at least 30 sec (or more). Sounds like a small vacuum cleaner to me.

If you don't hear the noise then check the electrical connections and fuse (40A fuse on the relay board next to the DME), and the relay (position 10 on the same board).

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P0410 Secondary Air Injection System - Signal Implausible (Cylinders 1 - 3)

P1411 Secondary Air Injection System - Signal Implausible (Cylinders 4 - 6)

Potential causes:

Secondary air injection pump is not triggered. - Wiring harness or fuse

Secondary air injection pump does not work. - Relay

Air supply lines restricted. - DME control module

Electric change-over valve does not work. - Air supply lines

Air change-over valve does not work. - Secondary air injection pump

Vacuum system leaks. - Electric change-over valve

- Air change-over valve

Did you or someone disconnect the secondary air pump?

I would start by checking for the noise when you start the car cold - the secondary air pump should run at least 30 sec (or more). Sounds like a small vacuum cleaner to me.

If you don't hear the noise then check the electrical connections and fuse (40A fuse on the relay board next to the DME), and the relay (position 10 on the same board).

Hi Loren,

Thanks for the response. I did check the air pump (its in the left side of the engine bay, just in front of the coolant tank, right ?) this morning and it seems to be up and running. It maked a mini-vacuum like sound and also hums/vibrates when touched (to confirm the source of the noise).

Should I open the pump or see if something at the hose intake is blocked ? What next my faithful guru !

Thanks !

Sid

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I would start looking at lines and the change over valves for leaks and blockages.

post-2-1153948546_thumb.jpg

1 - Secondary air injection pump

2 - Air change-over valve

3 - Electric change-over valve

4 - Non-return valve

5 - To the cylinder heads

6 - Vacuum reservoir

7 - To the intake air system

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I would start looking at lines and the change over valves for leaks and blockages.

post-2-1153948546_thumb.jpg

1 - Secondary air injection pump

2 - Air change-over valve

3 - Electric change-over valve

4 - Non-return valve

5 - To the cylinder heads

6 - Vacuum reservoir

7 - To the intake air system

Hi Loren,

Well, I took a shot at that just some time back. Lost the battle :(

A) I was able to verify that the pump works - apart from the sound it was blowing air with quite some force. I simply disconnected the hose and started the car cold and touched the pump outlet to feel the air. So the pump appears to be good.

Then I tried to find the air change-over valve but found it deep in the engine bay.

B.) How do I access the air change-over valve and how should I verify that it works ok ?

C) Next I tried #3 in your diagram, the Electric change-over valve. I was lucky to notice this just to the left of the throttle body (and verified the part # on the part with the drawing and part # in PET). So reaching this part wasn't an issue. I wasn't sure how to test if the part works or not. This part has two small male connectors (for tubes) and a small dime sized removable cap on its body. I blew air into one end of the small connector but couldn't feel it come out from the other end. Also, do I do something with that removable cap ? Basically, how can I test if that part is ok or not ? This one is very accessible so I'd love to check this first - just in case !

D) Most of the other components seem quite inaccessible (I had removed the air pump, air box/filter, throttle body). Is there a chapter or TSB/document which describes how to service this system ?

I really want to give this one more shot but feel I don't have the know-how :( ... yet !

help is greatly appreciated !!

cheers !

Sid

Edited by siddharth

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From the ODB II manual:

"Check electric change-over valve.

1. Remove two-pole connector of change-over valve.

2. Connect voltmeter to pin 1 (positive) and pin 2 (negative).

3. Trigger AIR pump with Porsche System Tester 2.

Display: battery voltage

4. Remove vacuum hose of change-over valve with the engine running. Check whether vacuum is present.

Check air change-over valve and air supply lines.

1. Run engine briefly to produce vacuum.

2. Trigger AIR pump with Porsche System Tester 2.

3. Remove vacuum hose of air change-over valve. If vacuum is present at the air change-over valve, check air supply from the AIR pump to the change-over valve to the air supply line to the cylinder heads.

Check function of air change-over valve."

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Here is what I would do. Assuming that the pump is working.

With the engine running, remove the vacuum line for item #3 that goes to the vacuum reserve canister #6. There should be constant vacuum. If not, the other end of the hose is disconnected from #6 and your air changeover valve will not open.

Next, on a cold engine, remove the other vacuum line from item number 2. Start the car, at which time the pump should start. You should be getting a vacuum in the disconnected line until the pump shuts off. If not,. problem is with the electric changeover valve #3.

On the other hand, you can immediately jump to the end and remove the larger hose from the non return valve (#4). On a clod engine, the pump should start and there should be air blowing out of the hose. When the pump shuts off, the blowing will stop completely. If this is the case, then you can safely assume that everything before this point back to the pump is working as designed.

The function of the system is simple. There is constant vacuum to the change over valve to which a vaccum line to the air valve is connected. When off, the changeover valve does not allow vacuum to get to the air valve. When on, (pump running) the valve activates and allows vacuum to get to the air valve and allows air to pass into the manifold through the one way valve.

Jim

Edited by 1999Porsche911

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Loren and Jim - Thank you, both of you. Jim, you remind me of my engineering professor. Explaining the system, then the purpose of the system ! I really liked it.

So I just checked the part #3, the Electric change-over valve. It was a good idea to hit the simplest target first since I think its broken ! I've attached an image of the part with some comments.

post-8807-1154367352_thumb.jpg

A) So it appears like the part needs to be replaced, right ? PET shows the part as 996-605-123-01 but the actual part in my car is 996-605-123-00. The last digits are usually just revisions right ? So the **-01 should work just right as my **-00's replacement ?

B.) Should I replace this part or is it servicable ? I think I should just replace it but out of curiosity I thought I'd ask you guys the next question ... that part has a removable cap at one end (see pic above) and I tried looking inside it. I couldn't make much out (thin and dark hole + didn't have a flash light around). I put a wire inside to 'feel' it, it feels spongy. Should I pry it open and get rid of the spongy stuff ?

C) Till I replace the faulty electric change-over valve, is it safe to drive the car ? I believe that this is only for cleaner emissions, supplying additional air to the exhausts to completely burn out residual wastes in the catalytic convertor. So while I might have mother earth cross with me for the next few days, I should be ok otherwise, right ? I'll plant a few more plants this week to soothe my conscience ! Also, no other P-codes other than the two listed ....

Finally, You guys rock ! I'm sure you've heard it before, but I really mean it. It's so satisfying to learn about and then fix your own car issues. Sincere thank you.

cheers !

Sid

Edited by siddharth

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Loren and Jim - Thank you, both of you. Jim, you remind me of my engineering professor. Explaining the system, then the purpose of the system ! I really liked it.

So I just checked the part #3, the Electric change-over valve. It was a good idea to hit the simplest target first since I think its broken ! I've attached an image of the part with some comments.

post-8807-1154367352_thumb.jpg

A) So it appears like the part needs to be replaced, right ? PET shows the part as 996-605-123-01 but the actual part in my car is 996-605-123-00. The last digits are usually just revisions right ? So the **-01 should work just right as my **-00's replacement ?

B.) Should I replace this part or is it servicable ? I think I should just replace it but out of curiosity I thought I'd ask you guys the next question ... that part has a removable cap at one end (see pic above) and I tried looking inside it. I couldn't make much out (thin and dark hole + didn't have a flash light around). I put a wire inside to 'feel' it, it feels spongy. Should I pry it open and get rid of the spongy stuff ?

C) Till I replace the faulty electric change-over valve, is it safe to drive the car ? I believe that this is only for cleaner emissions, supplying additional air to the exhausts to completely burn out residual wastes in the catalytic convertor. So while I might have mother earth cross with me for the next few days, I should be ok otherwise, right ? I'll plant a few more plants this week to soothe my conscience ! Also, no other P-codes other than the two listed ....

Finally, You guys rock ! I'm sure you've heard it before, but I really mean it. It's so satisfying to learn about and then fix your own car issues. Sincere thank you.

cheers !

Sid

If you want to confirm that the electric changeover valve is the problem, you can switch it with resonance valve changeover valve that is just above the alternator. Simply remove the 2 switches and swap them. It is safe to drive the car.

Edited by 1999Porsche911

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If you want to confirm that the electric changeover valve is the problem, you can switch it with resonance valve changeover valve that is just above the alternator. Simply remove the 2 switches and swap them. It is safe to drive the car.

uh oh. If that's where the "other" value is located then I think I was testing the "other part". The part I tested was just above the alternator, on the left side of the engine bay, behind the plastic air ducts (airbox intake)

So was I testing the "resonance valve changeover valve" instead of the electric change over valve ?

How do I locate the electric changeover valve ?

post-2-1153948546_thumb.jpg

Loren's diagram shows the connection very clearly but doesn't indicate where in the engine compartment the part is at. Part #2 and #4 are deep inside the engine bay, so I cannot follow the pipes to locate the part in question (#2).

**** ... I thought I had nailed this down ...

Edited by siddharth

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Should be right behind the cool air intake duct for the air cleaner (left side of engine).

Well, a picture is worth a 1000 words, so I used my camera phone to get this ...

post-8807-1154588359_thumb.jpg

So the part which I've circled in RED is the "right" part (i.e. #3 in your diagram or the electric air change over valve) ? This is the part which I tested and appears to have failed. I'm planning on replacing that part today if you guys can confirm that is the part labelled as #3 in Loren's diagram.

Sorry for the confusion but I used to think the part circled in red was the alternator and Jim mentioned that the "other valve" was above the alternator ... that's why I got confused.

Thanks

Sid

Edited by siddharth

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The valve above the alt. is for the resonance valve on the intake. The valve you are interested in is mounted to the engine case as shown below circled in red.

post-4060-1154556259_thumb.jpg

Todd

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You need to remove the alternator for easy access to the changeover valve.

Ok ... man, that really clears a lot of confusion. I get what you're saying. I'm at work right now, so I can't access the car. Any TSB's / factory manual chapter/page where they have instructions for safely removing the alternator from a 1999 996 C2 6-speed manual ?

UPDATE: The CEL turned OFF my drive back home ?! WTH ?? Is this normal / ok ? I'm thinking I'll still look into this once I get some direction on getting the alternator off.

UPDATE2: The CEL came back on last evening. I guess I will have to dive deeper. Anyone with a guide on removing the alternator ??

Edited by siddharth

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If you want to confirm that the electric changeover valve is the problem, you can switch it with resonance valve changeover valve that is just above the alternator. Simply remove the 2 switches and swap them. It is safe to drive the car.

I switched the resonance valve changeover valve (above alternator) with the Electric change-over valve (#3 in the figure below).

post-2-1153948546_thumb.jpg

I now get the same codes i.e.

- P0410

- P1411

- P1125 (new code)

1) The same codes as before means that my original #3 may not/may be faulty but also that :-

a.) The "replacement" resonance valve also died when I swapped it to its new position with earlier #3.

b.) The Air-change over valve (#2) is also dead

c.) The non-return valve (#5) is also dead

Question: To isolate the issue from the above possibilities (?), how can I test if air is blowing out from #5 or #2 ?

Problem: I'm able to access #5/#2 (to feel air blow on my hand) only when I've ripped out the air-box, alternator, tension belt ... I'd hate to reassemble -> disassemble -> reassemble the whole setup between different tests to isolate which part is bad (between a,b,c above). If there is no other way, too bad for me, but if there is please enlighten !

Recollect that I've tested the air pump to be working !

2) I'm thinking that the new code (P1125) might be because I've now put a faulty(unconfirmed since the old codes are still around) valve in the resonance valve's place.

Question: Does the above sentence make sense to you guys ? Or is that a new thing altogether ?

I'm trying to bulletize ideas to avoid confusion :( ... hope its working !

cheers guys - and thanks in advance !

Sid

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Are you clearing the codes before you swap the parts and retest the setup?

To test the vacuum valves rather than swap them around simply hook them up to 12V. This causes the valve to open. When open you should be able to blow throw the valve. When closed you should not be able to pass air through the valve.

Todd

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Remove the large hose from item #1. Disconnect the vaccum line from the electric change over switch that goes to the air valve #2. Apply a vacuum to the line (find someone who sucks well) and you should be able to blow through the large hose. If not, remove air valve and inspect it further. Item $5 is simply a check valve.

If the airp pump is working and the changeover valve is working, it can only be a bad air valveor the wiring to it.

Edited by 1999Porsche911

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Thanks guys !!

So I rigged up a 12 volt source with a (9v + 2x1.5v) batteries. Then I tested both the electrical air-over valves (the #3 in the diagram above as well the one above the alternator). Both seem to actuate properly and I can blow thru them when activated. When not actuated, the pipe seems blocked - just as expected.

Then I tested the air change over valve by applying some suction force on the small pipe and then having a hair dryer try to blow thru the same pipe as the air pump. Nothing seems to come out from the other side, so I'm assuming that the air-over valves are bad !!

I'm glad to at least find what's bad. Loren, the air change over valve I pulled out is 993-* and PET shows a part 993-* as well as 996* for the same part (air change over valve). Which one should I buy as the replacement ? Mine is a 99 996 C2.

I plan on ordering the replacement part via Sunset Porsche. Actually I'm planning on also replacing the 2x electic change-over valves ... since I've dig up so deep and they are ~ $20 a piece.

Also, based on my findings of a faulty air-over valve, do the 3 OBD2 codes add up fine ?? Especially the 3rd one (P1125)?

Cheers !!

Edited by siddharth

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For a MY 99 the 993.113.245.01 is the correct part.

Sometimes one fault can cause another fault.

Whew ! Thanks Loren, I picked up replacement parts for this and finished the job. the problem was a bad air change-over valve. But I also changed the electric change over valve since its just $20 but its deep inside. I did a post-mortem of the problem by editting the 1st post in this thread. Will post a DIY article on getting the generator out when I get another lazy day !

Cheers !!

Sid

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Loren and All,

I've got a 2000 996 Cab-4 and am doing the CEL PO410 + P1411 fix recorded in this string. When I got the alternator off I found the electric changeover valve for the secondary air injection system with no problem, but what should be the mechanical shutoff / changeover valve (part # 993 113 245 01) doesnt look like it does in the diagrams. It doesnt appear to connect to a check-valve or non-return valve. Here is a photo of what I am seeing:

post-7304-1190674183_thumb.jpg

Is this the right part to change?

Also, while doing this job I had to take out the airbox so took the opportunity to clean the throttle-body butterfly valve. Thanks for the tip!

Take a look at my "non-secondary air injections system electric changeover valve", the one easily accessible without removing the alternator, doesnt it look like a vacuum line has broken off of it? I cant find a loose line anywhere that might have mated up with it...

post-7304-1190674200_thumb.jpg

Thanks very much in advance for taking the time to respond.

Jeff

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Turns out Porsche replaced the seperate shut-off and check valves with one combined valve starting in MY2000. For some reason my 2005 PET did not have it listed. My local dealer says the new part number is 996 113 249 02.

Hope this helps everybody with 2000 or newer cars when they do the CEL P0410 + P1411 repair.

I am going to post my question about my possible vacuum leak in a new topic.

Cheers.

The pictures and diagrams before yours (vette67) are from a MY99 car and slightly different from your MY00 egas car.

I am sending you a PM with more info...

Edited by vette67

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