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P0412 code

billygee

New CEG'er
Joined
Mar 23, 2006
Messages
15
Hi guys. Thought I would come here for help with my '96 Sable LS, automatic tranny with the 3.0L Duratec engine after you helped me with my '95 Mystique.

3 weeks ago a mechanic replaced all the spark plugs and wires, apparently he had to take off the upper intake manifold to replace the rear bank plugs. Car was running perfect prior to the plug change.

100-200 kms later, the engine has been idling smooth with an occasional stutter, but misses and bogs down when accelerating. It seems to smooth out in the higher revs with an occasional miss. The Serice Engine Soon light came on and my friend pulled out a P0412 error code. No other codes in memory. Code was erased and the light came back on after just 5 minutes, same error code.

Mechanic says it ran fine when he gave it back to me, refuses to bother checking into it.

A search of the forums for that code showed up this: "P0412 Secondary Air Injection System Switching Valve A Circuit Malfunction".

Anyone have any ideas? Could this be the reason it's missing and bogging down? I don't want to take it to the Ford dealer yet as I can't afford much right now.

TIA!
 
From Ford CD,

Secondary Air Injection (AIR) System Monitor Electric Air Pump System
The Secondary Air Injection (AIR) System Monitor is an on-board strategy designed to monitor the proper function of the secondary air system. The AIR Monitor for the Electric Air Pump system consists of two monitor circuits: an AIR circuit to diagnose problems with the primary circuit side of the Solid State Relay (SSR), and an AIR Monitor circuit to diagnose problems with the secondary circuit side of the Solid State Relay. A functional check is also performed that tests the ability of the AIR system to inject air into the exhaust. The functional check relies upon HO2S sensor feedback to determine the presence of air flow. The monitor is enabled during AIR system operation and only after certain base engine conditions are first satisfied. Input is required from the ECT, IAT, and CKP sensor, and the HO2S Monitor test must also have passed without a fault detection to enable the AIR Monitor. The AIR Monitor is also activated during on demand self-test.

The AIR circuit is normally held high through the SAIR Bypass solenoid and Solid State Relay 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.
The DTC associated with this test is DTC P0412.

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.
l Key off.
l Disconnect SSR.
l Key on, engine off.
l Measure voltage between B+ circuit at SSR vehicle harness connector and battery negative post.
l Is voltage greater than 10.5 volts?
Yes
Supplied voltage is OK, GO to «HM2».
No
GO to «HM6».

HM2 CHECK CONTINUITY OF EAIR CIRCUIT
l Key off.
l Solid State Relay disconnected.
l Disconnect AIR bypass solenoid.
l Remove Secondary Air dedicated fuse temporarily.
l Disconnect PCM. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
l Install breakout box, leave PCM disconnected.
l Measure resistance between EAIR circuit at SSR vehicle harness connector and Test Pin 70 at the breakout box.
l Measure resistance between EAIR circuit at the AIR bypass vehicle harness connector and Test Pin 70 at the breakout box.
l Is resistance less than 5.0 ohms?
Yes
GO to «HM3».
No
SERVICE open EAIR circuit. REMOVE breakout box. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM3 CHECK EAIR CIRCUIT FOR SHORT TO POWER AND GROUND
l Key off.
l AIR bypass solenoid disconnected.
l Solid State Relay disconnected.
l PCM disconnected, breakout box installed.
l Measure resistance between Test Pins 70 and Test Pin 51, 71, 90, 97 and 103 at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
The EAIR harness is OK. GO to «HM4».
No
SERVICE EAIR circuit for short. REMOVE breakout box. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM4 CHECK EAIR CIRCUIT FOR SHORT TO POWER AND GROUND
l Key off.
l Reconnect AIR bypass solenoid.
l Solid State Relay and PCM disconnected, breakout box installed.
l Measure resistance between Test Pin 70 and Test Pins 51, 71, 90, 97 and 103 at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
EAIR circuit with AIR bypass solenoid OK. GO to «HM5».
No
REPLACE AIR bypass solenoid. REMOVE breakout box. RECONNECT components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM5 CHECK EAIR CIRCUIT FOR SHORT TO POWER AND GROUND
l Key off.
l AIR bypass solenoid disconnected.
l Reconnect Solid State Relay.
l PCM disconnected, breakout box installed.
l Measure resistance between Test Pin 70 and Test Pins 51, 71, 90, 97 and 103 at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
If P0411 or P1411 are also present:
GO to «HM9».
All others:
REPLACE PCM. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».
No
REPLACE Solid State Relay. REMOVE breakout box. RECONNECT components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM9 CHECK FOR VACUUM AT AIRD VALVES
l Key off.
l Reconnect PCM.
l Disconnect vacuum control line from the AIRD valve(s).
l Key on, engine running.
l After a 5 second delay, vacuum will be present between 30-90 seconds.
l Is vacuum present at the AIRD valve(s)?
Yes
GO to «HM10».
No
GO to «HM30».

HM10 CHECK AIRD VALVE(S) INTEGRITY
l Key off.
l Reconnect vacuum control line.
l Disconnect air tube from AIRD valve(s) outlet side.
l Cork off the air tube to prevent exhaust gases from escaping.
l Inspect AIRD valve(s) outlets for damage from hot exhaust gases. Service as necessary. Caution must be observed while performing this test.
l Key on, engine running.
l After a 5 second delay, air will be present between 30-90 seconds.
l Is air present from the AIRD valve(s)?
Yes
GO to Shop Manuals to service the exhaust tubes from the AIRD Valve to the exhaust manifold(s). COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».
No
SERVICE hose from EAP to AIRD Valve. If OK, REPLACE the appropriate AIRD Valve(s). RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM30 CHECK VACUUM HOSE INTEGRITY
l Key off.
l Check vacuum hose between AIRB solenoid and AIRD valve.
l Check for blockage and restrictions.
l Check for leaks and cracks.
l Check for kinks or disconnects.
l Are the above checks OK?
Yes
GO to «HM31».
No
REPLACE the vacuum line connecting the AIR bypass solenoid to AIRD valve(s). COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM31 CHECK AIR BYPASS SOLENOID ELECTRICAL OPERATION
l Key on, engine off.
l Connect Scan Tool.
l Enter Output Test Mode (OTM). Refer to «Section 2A», Diagnostic Methods.
l Disconnect AIR bypass solenoid.
l Connect DVOM to AIR bypass solenoid vehicle harness connector.
l Turn the outputs on, then turn outputs off while observing DVOM.
l Does EAIR circuit voltage cycle greater than .5 volt?
Yes
REMAIN in Output Test Mode. GO to «HM32».
No
GO to «HM33».

HM33 CHECK AIR BYPASS SOLENOID RESISTANCE
l Key off.
l Disconnect AIR bypass solenoid vehicle harness connector.
l Measure AIR bypass solenoid resistance.
l Is resistance between 50-100 ohms?
Yes
GO to «HM34»,
No
REPLACE AIR bypass solenoid. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM34 CHECK VPWR CIRCUIT VOLTAGE
l Key on, engine off.
l AIR bypass solenoid disconnected.
l Measure voltage between VPWR at the AIR bypass solenoid vehicle harness connector and battery ground.
l Is voltage greater than 10.5 volts?
Yes
GO to «HM35».
No
SERVICE open VPWR circuit. RECONNECT AIR bypass. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM35 CHECK CONTINUITY OF EAIR CIRCUIT
l Key off.
l AIR bypass solenoid disconnected.
l Disconnect Solid State Relay.
l Install breakout box, leave PCM disconnected.
l Measure resistance between Test Pin 70 at the breakout box and EAIR circuit at the AIR solenoid bypass vehicle harness connector and at the Solid State Relay vehicle harness connector.
l Is resistance less than 5.0 ohms?
Yes
GO to «HM36».
No
SERVICE open EAIR circuit. RECONNECT components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM36 CHECK EAIR CIRCUIT FOR SHORT TO GROUND
l Key off.
l AIR bypass solenoid disconnected.
l Solid State Relay disconnected.
l Breakout box installed, PCM disconnected.
l Disconnect Scan Tool.
l Measure resistance between Test Pin 70 and Test Pins 51, 76 and 91 at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
GO to «HM37».
No
SERVICE short to ground. RECONNECT components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM37 CHECK EAIR CIRCUIT FOR SHORT TO POWER
l Key off.
l AIR bypass solenoid disconnected.
l Solid State Relay disconnected.
l Breakout box installed, PCM disconnected.
l Measure resistance between Test Pin 70 and Test Pins 71 and 97 at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
REPLACE PCM. RECONNECT components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».
No
SERVICE short to power. RECONNECT components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».
 
Last edited:
From Ford CD,

Secondary Air Injection (AIR) System Monitor Electric Air Pump System.

Wow. Guess I will have to wait till I get my service CD next week so I could find where these parts are.

Thanks Tony, at least I have a starting point.

One other thing, when I was pulling the plug wires while the engine was running to see if perhaps I have a bad plug or wires by watching for any differences in the engine running, I noticed when I pulled the wire boot out fully on the 3 front cylinders, the boot insulator end was arcing across to the metal at the top of the valve cover when held approximately 3/8 inch away. I doubt that is normal right? Could it be the stumbling is caused by the plug boots being bad and arcing acorss to the valve cover rather than thru the spark plug?

Last time I did mechanical work was way back on the old muscle cars. When we checked for a spark, we would insert a small screw driver into the boot and bring it close to the valve covers to check for a spark arcing from the screwdriver to the cover or bolt. The boot insulators themselves would not create a spark. Could I have been given defective wires?
 
Last edited:
After replacing the plugs, wires and tracing my misfire to a loose connector on the #4 injector, the car ran perfectly however the SES light remained on.

As per Tony's suggestion I removed the battery cables for a while to reset the computer and after I connected it back up, the SES light remained off even after driving for a bit.

Must have been that loose injector that turned the light on.
 
It usually takes two consecutive drive cycles with the fault present to set the SES.....a short drive won't do it most of the time.

Steve
 
Damn. SES light came back on, same error code.

Took it for the emissions test today and while idle speed tests passed, the 40 kph tests failed. Have an appt on thursday for a full diagnostics so I could see exactly what needs to be done in order to pass the e-test.

I suspect the P0412 code is what is causing it, but I have no way of testing the parts or even finding them myself so I could test them. The flow chart Tony posted further up is beyond me as I am more of a remove and replace kinda person, lol.

E-testing terrifies me way more than safety checks do lol. At least with a safety check I know exactly what needs to be fixed but with e-tests, you have to pay $90 and up for them to tell you what part(s) are causing it to fail. That's AFTER the initial test (which costs $35) that you failed, and then another $15 for every test after.
 
P0412 fixed

P0412 fixed

After getting the Ford CD I ordered and going thru it checking where all the parts were, I set to checking out why the light came on. Air pump and relay passed all the tests so those were not the problem. Found there was NO power going to the relay so checked even further and finally found in the manual that the secondary air injection system was fused with a mega fuse. Checked the fuse under the hood and saw it was blown.

Replaced it with a new one, cleared the code with my OBD-II scanner, and drove it thru several cycles as per the Ford CD and the light never came back on.

Scanned it again after I got back and NO codes present.
 
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