P0411 Fault - Running Out of Ideas

200thhorseman

Active Member
Apr 11, 2015
5
0
Dear all,

Over the past couple of weeks I have been trying to diagnose a P0411 code following the check engine light coming on on my dashboard. My car is a 2004 Ibiza 1.8 FR 20VT and I am trying to fix this fault so I can sell it, therefore I don't really want to take it to the garage unless I have to.

I have been researching this fault both on Google and on this forum and understand this to be an issue with the secondary air injection system. So far I have tried and/or discovered the following -


  • The secondary air pump doesn’t appear to run at all when the engine is started, either hot or cold. No air is emitted from the hose from it, and no noise is heard from the pump. I have taken the pump out and checked the connector with a multimeter and no voltage is present on the pump connector. I also noticed quite a lot of water in the pump itself and the hose between it and the combination valve - is this just condensation?

  • The vacuum is OK up to the solenoid valve (N112) however there is nothing beyond it (i.e. in the pipe between the solenoid valve and the combination valve). The solenoid valve works OK if 12V is put directly to the pins, however it doesn’t open when plugged in. I checked the solenoid valve connector and there is only 8V on it, I'm guessing this should be 12V. Oddly I also noticed that there is 6V between the negative pin in the connector and the battery negative so I suspected a bad earth. I have removed and cleaned all of the earth points that I can find in the engine bay however this hasn't cured this problem.

  • The combination valve works OK when operated manually (i.e no air can be blown into the large pipe connected to it unless there is a vacuum on the small pipe).

  • All relays work OK. They latch when 12V is applied to power pins, and have good continuity and low resistance (less than 0.01 Ohms) between the other pins.

  • Fuse S176 (secondary air pump) in the fuse box above the battery is fine.

Note that I replaced the intake air temperature sensor about a month ago as I was getting a check engine light and a P0114 fault. This fault has gone however now I get the P0411. Could this have anything to do with it?

Any additional guidance or help that anyone can offer will be gratefully received.

Regards,

Rob
 
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