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2000 Ford Taurus FFV P0412 Code: Diagnosis and Fix for Secondary Air Injection System

Model: 2000 Ford Taurus FFV Fault Code: P0412 Posted: 2014-08-14 17:18

I own a 2000 Ford Taurus with a 3.0L 2-valve engine, currently at 137,000 miles. I'm experiencing a Check Engine Light (CEL) triggered by fault code P0412 — indicating insufficient secondary air injection system operation. I tested the secondary air injection pump directly using a 12V battery connection and confirmed it operates properly when powered. However, when the key is turned on, I am not receiving adequate voltage to the pump. I have already checked the relay and found it to be functional. This model does not feature a solid-state relay mounted directly on the air pump assembly. Could anyone provide guidance on troubleshooting this issue? Specifically, how to verify proper power delivery to the secondary air injection system components?

Related fault codes
P0412
Comments (8)
Anonymous 2014-08-14 21:19

Did you check for 12V at fuse #111 and #128 under the hood? Is there 12V present on the red wire connected to the air pump solenoid (secondary air injection bypass solenoid)? A disconnected or open AP solenoid can cause P0412. If voltage is absent at this point, that may be the root issue. Note: The pump does not run continuously — it only activates when commanded by the Powertrain Control Module (PCM). Ensure the circuit from the relay to the air pump is intact. Do not confuse the solenoid with the relay.

Anonymous 2014-08-15 13:42

Thanks for the reply. I've confirmed both fuse #111 and #128 have 12V when the key is on. However, there is no voltage detected on the red wire leading to the air pump solenoid. The relay itself also shows 12V when powered.

Anonymous 2014-08-15 17:14

The red wire supplying power to the solenoid is only energized when the PCM sends a command — not during key-on alone. If there's no voltage at the solenoid, this indicates a failure in the PCM-controlled circuit. Without proper signal from the PCM, the relay won't activate, and P0412 will be triggered.

Anonymous 2014-08-15 21:26

Could you please specify which solenoid and where it is located on the vehicle?

Anonymous 2014-08-16 15:28

The bypass solenoid is typically located near the ignition coil and capacitor assembly, underneath the engine. It has two wires with a connector — both should show 12V when the key is on. Vacuum lines may be connected to this component as well. Unfortunately, I cannot provide a diagram here.

Anonymous 2014-08-16 16:14

I tested the bypass valve and confirmed it receives 12V when the key is turned on — suggesting power delivery is present at that point.

Anonymous 2014-08-18 11:05

After disconnecting the negative battery terminal for 30 seconds, the check engine light has not returned. I've driven the vehicle for two days with no CEL activation. There's one incomplete diagnostic monitor remaining — this is acceptable and should allow CA emissions compliance.

Anonymous 2014-09-04 09:09

The check engine light is currently on, and a scan revealed both P0412 and P0401 (Engine Exhaust Gas Recirculation Flow Insufficient). What steps can I take to resolve these issues?