P0416: Secondary Air Injection System Switching Valve B Circuit Open

Quick answer

• What the code means: The P0416 code means that the engine's computer (the powertrain control module, or PCM) has detected an open circuit in the secondary air injection system's switching valve 'B'.
• Severity: Low. It is generally safe to continue driving your vehicle with this code, but you may fail an emissions test.
• Most common cause: The most common cause of the P0416 code is a faulty secondary air injection switching valve.

What the P0416 code means

The official OBD-II definition for P0416 is "Secondary Air Injection System Switching Valve B Circuit Open." In plain English, this means the powertrain control module (PCM) has detected a problem with the electrical circuit for the 'B' switching valve in the secondary air injection (AIR) system. This is an emissions-control system that pumps fresh air into the exhaust for a short period on cold starts to help the catalytic converter warm up faster and burn off excess hydrocarbons.

The PCM monitors the AIR system's electrical circuits, and if it sees a break or opening in the circuit for the 'B' switching valve (which is what "circuit open" means), it will set the P0416 trouble code and illuminate the Check Engine Light.

Common symptoms

Because the secondary air injection system only operates for a minute or two on a cold start, you are unlikely to notice any driving-related symptoms. The most common symptom is simply:

• Check Engine Light is on
• Possible noise from the AIR pump
• Your vehicle may fail an emissions test

Common causes

The causes for P0416 are almost always electrical in nature. Here they are, ranked from most to least likely:

1. Faulty AIR switching valve 'B': The valve itself can fail internally, causing an open circuit.
2. Wiring or connector issues: Damaged, corroded, or loose wiring or connectors in the switching valve circuit are a common culprit.
3. Blown fuse or faulty relay: The circuit is protected by a fuse and controlled by a relay, either of which can fail.
4. Faulty AIR pump: While less common for a circuit-specific code, a faulty AIR pump can sometimes cause electrical issues that trigger a P0416.
5. PCM issues (rare): In very rare cases, the powertrain control module itself may be faulty.

How a technician diagnoses it

A technician will use a systematic approach to diagnose a P0416 code. Here are the typical steps:

1. Scan the vehicle for codes: The technician will connect a professional scan tool to the vehicle's OBD-II port to confirm the P0416 code is present and check for any other related codes.
2. Inspect freeze-frame data: They will analyze the freeze-frame data to see the conditions under which the code was set (e.g., engine temperature, RPM, etc.).
3. Visually inspect the AIR system: The technician will perform a thorough visual inspection of the AIR system's components, including the switching valve, pump, hoses, and wiring. They will look for any signs of damage, corrosion, or loose connections.
4. Test the switching valve circuit: Using a multimeter, the technician will check for proper voltage and ground at the switching valve connector. A reading of 0 volts would indicate an open circuit.
5. Test the switching valve: If the circuit checks out, the technician will test the switching valve itself. This can be done by using the scan tool to command the valve to open and close while listening for an audible click, or by applying battery voltage directly to the valve to see if it actuates.
6. Check fuses and relays: If the valve and circuit are good, the technician will inspect the related fuses and relays for the AIR system.

Typical repair cost

The cost to repair a P0416 code can vary depending on the cause and the vehicle's make and model. Here are some typical cost ranges:

• Diagnosis: Most shops charge a diagnostic fee, which is often applied to the final repair cost. This can range from $100 to $200.
• Wiring repair: If the issue is a simple wiring or connector repair, the cost could be as low as $50 to $150.
• Fuse/relay replacement: This is a very inexpensive repair, typically under $50.
• AIR switching valve replacement: The cost of the valve itself can range from $50 to $250, with labor adding another $100 to $200.

Can I keep driving with this code?

Yes, it is generally safe to continue driving with a P0416 code. The secondary air injection system is an emissions-control device and does not affect the engine's performance or reliability. However, the Check Engine Light will remain on, and you will likely fail an emissions test, so it's best to get it repaired as soon as you can.

Related codes

• P0410: Secondary Air Injection System Malfunction
• P0411: Secondary Air Injection System Incorrect Flow Detected
• P0417: Secondary Air Injection System Switching Valve B Circuit Shorted
• P0418: Secondary Air Injection System Relay 'A' Circuit Malfunction
• P0491: Secondary Air Injection System Insufficient Flow (Bank 1)

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