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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 33045
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ford F150: code PO411Secondary air injection system incorrect flow

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Im getting code PO411
Secondary air injection system incorrect flow detected. Any advise?
Vehicle is a Ford F150 with a 4.9 straight six.


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Diagnostic Trouble Code (DTC) P0412 indicates EAIR primary circuit malfunction.

Possible causes:

  • EAIR circuit open.
  • EAIR circuit short to power.
  • AIR bypass solenoid malfunction.
  • Solid State Relay malfunction.
  • Damaged PCM.

Enclosed is the complete pinpoint test.



Customer: replied 6 years ago.
My DTC is not PO412 its PO411



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Same circuit and similar test so here is the P0411 test.




Customer: replied 6 years ago.
Hi Ron, I'm sorry but I just don't follow. Do I still start with test for PO412? because I'm still getting the same printout. Also I'm not sure where to find the things to test. I just bought this truck and am not too familiar with it. Thanks for your patience. I did a lot of work on cars in the 60s and 70s This new stuff is a little confusing



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No if your code is P0411 , start there.


Let me try and make it a bit more simple , this problem is usually caused by bad switching valves. Start here.


This sounds like you may have a bad switching valve so run thru this test.

Access the Air Injection Reaction (AIR) Bypass solenoid below the ignition coil pack. Check for battery voltage to the White wire (from the 30-amp fuse #8 in the engine compartment fusebox), and backprobe the Brown wire with a jumper.

With the solenoid connected, ground the Brown wire and verify that the AIR pump runs. If the pump does not run, locate the AIR pump on the driver side front of the subframe. Unbolt and turn the AIR pump to access the solid state relay, which is mounted to the side of the pump. Verify that the White wire at the relay also has battery voltage from fuse 8, check for a good ground on the Black wire at the relay, and with the relay connected, ground the Brown wire there and check for battery voltage on the White/Orange wire to the pump. If no voltage is present on the White/Orange wire with the Brown wire grounded, replace the relay. If battery voltage is present on the White/Orange wire, and the Black wire on the pump is a good ground, but the pump doesn't run, replace the AIR pump.

If the AIR pump runs, monitor the Oxygen (O2) sensor operation in closed loop before and after energizing the AIR pump, by grounding the AIR relay Brown wire, to verify that both O2 sensors drop to lean readings within seconds of commanding the air pump on.

If only one O2 sensor reading drops lean quickly, verify that a vacuum signal is present to the switching valve on the side that did not drop quickly and replace the switching valve as necessary.


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