Update: fuses arrived for the multimeter. Fixed that, confirmed it's working.

Checked power to the secondary air pump connector - nothing. Then I realized there won't be power to that plug except for the 30-60 seconds (or however long) the pump is running at cold start.

Turned on the car, tried to check the power to the plug very quickly - still nothing.

60A fuse is good.

I figure there are three possible problems at this point: 1) relay, 2) a short somewhere between the battery and the plug, or 3) even though the pump is new, fan spins freely, and there is no condensation inside, maybe it's bad.

Please let me know if you have any thoughts.
-BR

 

Update #2:

I took the relay out in an attempt to buy a replacement. Showed it to the Auto Zone people, they didn't have one. In the meantime, the ECU threw a P0418 code - something about the secondary air circuit. That's the first time I've seen that code. I figure it has to do with the missing relay?

I also tried another diagnostic step - at the secondary air pump, I unhooked the hose that connects the pump to the two valves. I started the engine to see if I could see or smell exhaust coming from that hose. My thought was - if the valves are stuck open, the exhaust from the exhaust manifold might start pouring out of the hose. I saw and smelled nothing.

So - I reconnected the hose, reinstalled the relay (which may or may not be bad), and cleared the codes. Tomorrow morning I'll turn the car on and see what happens.

I'm wondering - if the ECU doesn't throw a P0418 code again, can I assume the relay is good?

And - any thoughts on how to cue the battery to send power to the pump? I'm still not sure how to check power at the secondary pump connector, since there's only power at that connector for 30-60 seconds at cold start?

Thanks.
-BR

 

Update #3:

Everything is back together the way it was when the fuse blew in the first place. Drove to work (very close) this morning, no CEL. But the air pump didn't come on, either. Drove home this evening, air pump no functioning, CEL came on immediately, P0410. 🤬

I really want to check the power situation. Any idea how to do that considering there isn't steady power to that connector? If I stand there with the multimeter in hand, and have someone turn on the car (cold start), I should expect to see power to that connector, right?

Or, should I order a replacement relay and see if that works? I don't think there's an easy way to check whether the relay I have is bad or good...is there?

Thanks,
BR

 

I'm following you, but I have no advice. Mine got removed because it was unsolvable

 

Following as well. I noticed when I cold start my car it almost drowns in fuel and chugs until the fuel is cleared out. I do not hear the air pump activate on cold starts. I used to hear a running water sound when i started my car and I believe there was water/ is water in the air pump tube. You can test your pump by using alligator clips and directly powering the air pump via the battery, but this will not tell you why it’s not firing up on cold start if the pump and relay are good.

I did see a guy on YouTube find that the secondary air pump isn’t an isolated circuit. It’s actually intertwined with other emissions systems (tgv’s) etc. I haven’t dove in much deeper than this. I sourced a used air pump to see if that will help. It would be nice to drive this car without this code. It’s been about 7000 miles since it came on.

 

When I had the system "fixed" in December, they told me the old air pump was full of water. So absolutely, the water does collect in the system (the pump and the valves).

I suppose testing the pump in that way would at least eliminate the possibility that the pump itself is bad. You can just use the car battery to do that? No need to disconnect the battery, use a separate battery, anything else?

7000 miles - damn. I feel you.

 

My car drives fine after the cold start sequence. It almost chokes out on fuel because it is expecting that air from the air pump but nothing comes through.

You can bench test the air pump off the car by using power leads connected to the car battery to the power connector on the air pump. This will tell you if the air pump functions in the first place.

 

What year is your car?

So this implies that all else being stock, if you delete the smog pump, you would need to adjust the tune to compensate for the lack of air the smog pump would otherwise be blowing into the exhaust manifold?

But - the exhaust manifold is post-combustion, isn't it? If so, how can the smog pump blow air into the air/fuel mixture and affect combustion?

Definitely talking out of my back pocket here, just trying to make sense of what I think I know.

On the subject of the boost (or lack thereof, in my case), I read somewhere the smog pump-related codes might limit the boost somehow? I would bet a week's pay that my boost has been affected ever since that 60A fuse blew in the first place. Not that I can prove it...

As far as the pump test, rather than remove it from the engine bay, I may try to test it as you describe as it sits in the car. I'll unplug it, then use the alligator clips to connect it to the battery and see if it whirrs.

What a goat rope.

 

Here's an old thread I found that might be related to this issue:

20 second stumble on cold start 2018 STi - Page 3 - NASIOC

Page 3- 20 second stumble on cold start 2018 STi Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo)

forums.nasioc.com

For my specific scenario, I'm on a OTS intake and downpipe tune with equal length headers. This issue popped up out of nowhere for me.

 

My car is a 2019 but this issue seems to affect 2015+ cars. From reading that thread, it seems that the choke can be minimized by a tuner but not completely eliminated. Also, I reset my ecu learning by accessport because it threw a p0172 rich code and the car runs noticeably worse than when the car is running with a check engine light. My issue is probably fine related honestly but who knows. I’m not looking to rip apart everything to fix it.

 

I know that feeling, the "easier and cheaper to leave it alone" feeling. I guess that's where my uninformed troubleshooting comes from - if it's something relatively straightforward, maybe I can fix it myself. Save the trouble and cost of taking it somewhere where they say "sure, I'll replace the whole system, that'll be $2000" or whatever. 😔

 

Update #4:

Diagnostic equipment (alligator clips) arrived in the mail this afternoon. Checked the pump by hooking it straight up to battery power...

And...

Nothing.

So, it appears the pump has died. Did I mention that I got the pump from the used car salesman who sold me the car? He sent it to me after I called him out for selling me the car without disclosing it needed $2000 worth of smog pump system work. But that's a different story (and not the whole story - it's actually worse than that)...

The plan now is to call the dealership, order a new pump, and use the $$$ voucher SOA sent me a couple of weeks ago to help pay for it. That was a small victory, to be sure. Thanks SOA!

Hopefully when the pump arrives, I can install it myself. The hardest part appears to be physically extracting the pump from its housing underneath that A/C line, and then shoving the new one down in there. Anyone done that job before?

Hope y'all are doing well.
-BR

 

My car turned off its check engine light today while retaining the P0410 code in memory. It’s done this once or twice before and I’m not sure why. I’m sure the car will throw the code again tomorrow morning.

I wonder if my upstream o2 sensor or connections have issues. I also ordered a used pump from eBay for $100. I would check there if you’re okay with a used pump.

 

Jeez, that is something. Why in the world would it do that? I suppose it could be that O2 sensor, but on a 2019 it shouldn't be ready to be replaced (needless to say). Maybe a connection, like you said? Not helpful that the P0410 code can mean anything it wants to mean. Not real helpful at all.

I am 99.467% sure that eBay (or somewhere) is where the used car salesman picked up this pump. And look what it got me - maybe 1000 miles. Ridiculous. I'd rather spend $350 of my money, $350 of the voucher, get a real one, and God willing it lasts forever (haha).

Now, if you can point me in the right direction to someplace with a good reputation for quality used stuff, I am definitely happy to save my voucher and cash to spend a lot less. That would be awesome, yes please.
BR

 

For some background on what happened to my car, a shop installer did not secure the O2 wire when installing the killer b equal length header on this car. This caused the wire to rest on the header runner and melt the sheathing.

When I replaced my O2 sensor, I ordered an extended wiring harness from Iwire to give the wiring enough slack to be tucked away from the header runner. Now I'm wondering if a similar issue happened on the sensor wiring I'll find out when I get a chance to work on the car again.

My solution is to find a tuner that can still disable codes or move on to open source tuning.

 

What can you tell a noob about open source tuning? I’m intrigued.

 

To make matters worse, my car didn't turn the check engine light on today. It retains the P0410 code in memory per accessport. The car runs and drives remarkably better than it did a day ago. The only thing I did yesterday was inspect my upstream O2 sensor wiring. I couldn't check the condition of the wiring, but I did check the connection quality [unplug / plug back in]. It's possible for my situation that the Iwire harness extension was causing issues by not having a great plug in connection.

 

Wow, great find. Maybe that was it?

i ordered my pump today from the dealer. Hoping the swap is doable and fixes the problem. Most of all, I’m also looking forward to see whether the car drives better / boost goes back to normal. Similar to your situation. I swear these things are connected.

Hope your ride stays CEL-free!

 

Welp, my luck ran out. Car threw a cel for p0410 again. Back to square 1.

 

Nooooo! 😩

How's the car driving? You mentioned that when the CEL went off, it started driving better?

 

Update #5:

Picked up the pump and a new relay (why not?) at the dealer this morning. Cleared the codes. Completed the swap (pump and relay). Buttoned everything back up. Now I'm just waiting for a "cold start" opportunity to see what happens. Wish me luck.

Shout out to subaruonly.com, where I found the repair instructions. They weren't complicated, but it definitely made me feel better to have them.

OEM on the left, generic on the right.

I had to disconnect the positive wire to the battery to give myself just enough wiggle room to remove the pump in its housing.

OEM FTW! Hopefully...

Have a good weekend.
-BR

 

Thanks for the write up. I received my replacement pump this weekend. Just need time to try to replace it. Hope yours is the solution you needed!

 

Final update:

I started the car cold, twice, the day after installation. I was listening for the same loud fan noise, the same noise that the old, broken pump used to sound like. I didn't hear it, and I felt sorry for myself. That was yesterday. However - no CEL.

This morning, I started the car and listened carefully. I thought I heard the pump's fan, maybe? It was very soft - pretty much drowned out by the engine. Nothing like the very loud, very distinguishable noise of the old fan. And still - no CEL.

Today after work, I popped the hood in the parking lot. Started the car and walked around to put my hand on the pump. It was working! Holy sh*t! I left my hand on the pump and savored victory until it cut off about 30 seconds later.

So there you have it - a long project, but successful in the end (knock on wood we don't have another setback in the near future). Good luck to everyone who's working through his or her own P0410 demons.
-BR

 

Hi, are you still CEL free after some time has passed? I had a chance to work on my car today and swapped out a used ebay air pump for my factory one. When I bench tested the two, I noticed that my factory one had much lower air output than the used ebay one. So hopefully this was the issue and my car remains CEL free for the time being.

 

How's it going, yes, I'm still CEL-free. The secondhand pump that was in my car definitely went bad - pulled too much power, for whatever reason, and fried itself (and two fuses as well).

That is interesting - maybe your factory pump was just dying? I hope it works and the CEL stays off forever 😂!

 

Very sad. My check engine light came back on for p0410. Time to look for someone who can make it not check engine light anymore.

 

Have you done the entire secondary air injection system service? The two valves, the pump, the relay, whatever else goes with?

 

I don't think I will go that route ha ha. I recently had my STI's up pipe switched to an aftermarket one due to excessive rattling from the oem heat shield. The parts installer found that there were excessive exhaust leaks where the headers meet the heads when they were installed by a high profile youtuber previously. Lesson learned, pay professionals, not youtubers. Hoping that removing some leaks will help my air pump function correctly.

 

Interesting that I also had an exhaust leak back in December when the smog pump system was fixed...

I'm told by more-or-less reputable sources that the secondary air injection system is a "closed" system and therefore shouldn't have anything to do with the exhaust, or turbo boost, or any of that. On the other hand, common sense dictates that when the smog pump system valves open and let air blow into the exhaust manifold, by definition, that is not closed - that is OPEN! In the event valves are stuck open, which definitely happens sometimes, I have to believe that the two systems (smog pump and exhaust) can affect each other? But what do I know 🙄...

Regardless, sealing up those leaks can't hurt. Let us (ok, maybe it's just me?) know how it goes.