New P0412 code

WickedWally

New Member
Jul 11, 2019
4
0
1
52
Somers, CT
Hey guys,
I had a secondary air system code p0411. I changed the air pump, relay, EVR, DPFE sensor, and vacuum solenoid. The code finally went away with the vacuum solenoid. Then the check engine light came on the next day. P0412. I don't know what it wants now.
 
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wmburns

SN Certified Technician
Aug 14, 2009
5,361
417
164
Houston Texas
What have you done to rule out an exhaust leak? The V6 is bad about the exhaust manifolds rotting out from water dripping on them. This creates a leak where the air isn't actually making it into the exhaust manifold.

Do both O2 upstream sensors work?

Do you have an ODb2 scanner? If so, this could be a huge help in trouble shooting without having to replace parts.

P0411 - Secondary Air Injection (AIR) system upstream flow
See DTC P1411​
P1411 - Secondary Air Injection (AIR) system downstream flow
The secondary air injection system does not detect the presence of air in the exhaust when introduced by the secondary air injection system
  • Electric AIR Pump
  • Hose from AIR pump leak
  • AIR bypass solenoid leak/blocked
  • Hose from AIR pump blocked
  • AIR bypass solenoid stuck open/closed
In order to test the AIR pump, it must be capable of driving the HO2S lean.​
 

WickedWally

New Member
Jul 11, 2019
4
0
1
52
Somers, CT
What have you done to rule out an exhaust leak? The V6 is bad about the exhaust manifolds rotting out from water dripping on them. This creates a leak where the air isn't actually making it into the exhaust manifold.

Do both O2 upstream sensors work?

Do you have an ODb2 scanner? If so, this could be a huge help in trouble shooting without having to replace parts.

P0411 - Secondary Air Injection (AIR) system upstream flow
See DTC P1411​

P1411 - Secondary Air Injection (AIR) system downstream flow
The secondary air injection system does not detect the presence of air in the exhaust when introduced by the secondary air injection system​
  • Electric AIR Pump
  • Hose from AIR pump leak
  • AIR bypass solenoid leak/blocked
  • Hose from AIR pump blocked
  • AIR bypass solenoid stuck open/closed
In order to test the AIR pump, it must be capable of driving the HO2S lean.​
 

WickedWally

New Member
Jul 11, 2019
4
0
1
52
Somers, CT
No exhaust leaks. New motor with just over 500 miles. Mechanic had to soak the intake for two days to clean out all the carbon deposits. All new gaskets when motor was put in. The code was leftover from the old engine. I replaced both upstream o2 sensors last summer. Yes, I have an Autel scanner and it kept giving me the P0411 code until I replaced the solenoid. Then it went away and left the P0412, which I thought was strange.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,361
417
164
Houston Texas
Anytime a DTC code calls out a "circuit malfunction" it means there is something soooooooooooo wrong with the circuit that the PCM is unable to perform any meaningful diagnostics. Think: Short, open, ground fault, wiring, crossed wires, broken connectors, rodent damage, water damage.

It's obvious that some of the other work has changed the symptom. In fact if this were my car I would be double checking all of my work especially anything involving anything electrical.

>>From Ford service manual
P0412 - Secondary Air Injection System (AIR) circuit malfunction
The PCM attempts to control when air is injected in the exhaust. The DTC indicates a Secondary Air injection system AIR circuit fault.
  • AIR circuit open
  • AIR bypass solenoid fault
  • Damaged PCM
  • AIR circuit short to power
  • Solid state relay fault
  • Damaged AIR pump
The AIR circuit is normally held high through the AIR bypass solenoid and SSR when the output driver is off. Therefore, a low AIR circuit indicates a driver is always on and a high circuit indicates an open in the PCM.​