2009 9-3 2.0T cel code help p2431 p0411

[noahgl]

Hey all. Never posted here so if I forget some info forgive me. I have a 2009 9-3 2.0T XWD and I've had p2431 (SAI air flow/pressure sensor/perf bank 1) and P0411 (SAI incorrect flow) codes for a while, I clear them and they come on in a week or so. With my inspection coming up which requires emissions I'm desperate at this point. In the past I replaced the valve on top of the engine because it was filled with soot, which helped for a while. Then when the light came on I replaced the SAI pump. I'm not sure what to do next and have done a lot of reading on this topic but most people just say to replace the valve which I already have. Any help will be great and don't really want to take it to a shop until I find out what it could be. Thank you

[Digger]

Soot is a tough word to work with, one person says soot and another says that's not soot, now this is soot. Either way with parts replaced and the problem persisting it's more a symptom than a cause.

When the air pump is on you should have air moving like a hurricane through that tubing, if the line is plugged, cracked, or loose, your air isn't getting where it needs to go with the pressure it should have, so check you air tubing. A relay turns on the air pump, if that relay is sticking your pump doesn't come on when it should. The relay gets turned on by sensors that feed signals and a loose connection at any point along the path can leave the relay waiting for the signal that tells it to power up the pump. Before you go buying things you might not need give this whole thing a good look see hands on physical inspection. Gently pull on wires that go into the plug ends, look inside the plug connects for a connector that looks to be a hair bit bigger than the other connectors. These are the little things don't need special tools, cost nothing to do and can keep you from spending good money to fix something simple.

Sometimes just reseating all the sensor plugs can solve a bad connection problem and if your problem goes away after your inspection great, if not there are voltages to check and tests to run, for that you need tools and a shop manual.

Depending on how much time you have between now and your inspection, you do what you can and have done what you can't.

[noahgl]

I replaced the fuse and a relay thats next to it, and after I did that the light went out and I could hear the air being sucked through the valve. But then when I started my car when I left work the light came on and got those same codes so I think it's electrical because now I know that atleast the valve turns on.

[Digger]

If you have a volt ohm meter and know how to use it, wiggling wire harness from end to end is the best place to start.

If not it's a coin toss for starting at the underside of the electrical center looking for a sparking loose connector, or where the wire harness clamps to the engine looking for worn insulation and wires that short when they wiggle.