Error codes P0410 and P1411 - strange result

Hi, my CEL recently came on on my 2001 C2 996. The P0410 and P1411 error codes suggest that during cold starts, the air from the secondary air injection pump was not making it through the air change over valve to the cylinder heads. The secondary air injection pump woks fine, but my examination disclosed that while 12V was making it to the air injection pump when activated, only 8.6 volts was making it to the little pierburg electric change over valve. The valve seemed to be shut which did not allow vacuum to pass from the vacuum reservoir to the air change over valve. Before I go looking to change the electric change over valve (fortunately reasonably priced and easy to access), I will see if I can put 12V through it to see if it will open. Any obvious (or not so obvious to me) reasons only 8.6 volts would get to the electric valve? Wiring harness and connectors seem clean and tight. Car has zero other scanner disclosed errors and runs well.

First find out if the valve is supposed to get 12V or 8.6V.

If you are in Dubai, isn't your car DME/ECU programmed ROW (rest of world)? ROW programming of the DME/ECU ignores secondary air injection faults. I believe only cars destined for North America were programmed to throw a CEL for secondary air injection faults.

The car is a U.S. spec car. I am not certain if the valve is supposed to get 8.6v or 12v, the Bentley manual is silent on that point.

That change-over valve should have a 12v potential. If you check the wiring diagram for your particular model, you will find the red/blue 12v potential wire is also joined to various other change-over valves, solenoids, vent valves ect. for engine components.

Here is the entire secondary air injection system. As far as I know, since the car is 12V, I don't know why there would be a step down to 8.6V to operate the valves.

Thanks everyone for all the suggestions, I could not think of any reason why the voltage would intentionally be reduced. Now the questions remain as to why the reduction in voltage at the plug and whether the valve is functional. To the best of my knowledge, the electric valve visible near the secondary air pump only serves one bank. The error codes suggest problems with both banks. If they are on the same circuit (likely) and they are both not opening, it would indicate either that (i) 8.6 volts is insufficient to open either valve, or (ii) both banks developed faults independently at the same time (and the fault of one bank is the valve). The former is more likely, but I will need to figure out how to conduct some voltage drop tests with the engine in place to locate the source of resistance. 911 engines generally are a pain to work around when in the car.

The electric change-over valve that is close the the SAI pump (mounted to the intake on a bracket) goes to the secondary resonance flap in the rear center plenum, does not control the SAI injection. You don't have your head wrapped around the components, their locations, or their function correctly. There is only one change-over valve for SAI, and it is not the one you have tested with the 8.6v ??

I erred when I assumed there were 2 of them (I thought that the order link on Pelican suggested I need two). Since I posted I have looked at pictures of my engine when it was out of the car and could not see a second valve. The part number is 7PP-906-270 and can be found at: https://www.pelicanparts.com/cgi-bin...n=7PP-906-270- Yes, that is the valve receiving 8.6 v. My guess is a bad ground somewhere, but I need to find it.

Had same problem on my '99', except no voltage at changeover valve for resonance flap. Think that is also what you are dealing with? Ended up running new wire along loom and splicing in. Was the white wire from pin #10 On connector X59/2. Your MY car might be different. Oops,. I think your code indicates poor or no air injection. Although your low voltage may have been taken at the changeover valve for resonance flap? Do you have a Durametric?

Start by making sure the engine ground strap (behind and ahead of the passenger wheel) has clean connectors. What is the voltage at the 12V+ post in the engine bay? Battery in good order? Voltage on cluster gauge while running? Might pull apart your X59 connectors and clean with electrical contact cleaner.

I have been driving from cold in the morning (ok, 'cold' in the early morning is about 30c here now) and driving it around town all day, At least first thing in the morning the secondary air injection pump has was running (I am unsure if it runs when the engine has a hot start, but I don't recall hearing it). No more error codes when I just checked it. Car still runs great. Any idea where that part of the loom is grounded? I was under the car today and did see a kind of ratty looking eyelet grounded on a bolt through a bracket by cylinder 1. I will clean that up, but it would be pure luck if that was the issue. Good idea about taking power elsewhere, but I suspect the issue is on the ground side.

Quotes source post: 16630842

If we are still talking about low voltage at changeover valve for flap, without a Durametric to activate circuit I don't know how you could get a reading. That valve activates at around 5000 RPM if not mistaken.

No, not for the resonance flap; to my understanding this valve *number 18 in the diagram above) allows vacuum through it, opening a second, larger vacuum operated valve (number 11), allowing air from the air pump to get into the engine during the first 10 seconds of warmup, in order to reduce emissions. I activate the secondary air injection pump using the Durametric, which causes power (only 8.6v) to reach the electric valve.

Quotes source post: 16630907

Okay, that sounds kinda correct. There are two #18's in that diagram though. The one for air injection is not easily accessible. Located under rear plenum I think. The other #18 is easily gotten too and will have a voltage when not activated. Mine shows 6.3 volts. I'm guessing when DME signals change over valve to open it completes circuit by grounding the valve. I think your 2002 is probably having no problems. May just need to exceed the speed limit every so often.

I will check the connectors and the ground connections and see if everything is clean and tight. Am I correct in assuming that the air pump does not turn on if the engine is above a certain temperature? I do see that there are two changeover valves in the diagram above, If the one in the middle of the diagram allows the engine to be fed air from the air pump, what does the second one at the bottom of the diagram do? I have assumed that the change over valve which is visible and easily accessible is the one of interest.

The change over valve that u can see goes to the rear cross over tube on the plenum for the resonence flap. The valve u want to test is next to where the oil dipstick tube enters the block. U will have to remove the tb and rear most crossover tube and maybe even the alt to get your hands in there.

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The second changeover valve behind the alternator is the one that opens the secondary air injection shut off valve. In the above, the most accessible changeover valve right next to the alternator operates the resonator as follows