P0416

Secondary Air Injection System Switching Valve B Circuit Open

P0416 is a generic OBD-II powertrain diagnostic trouble code: Secondary Air Injection System Switching Valve B Circuit Open. It is logged by the engine control unit when the egr monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0416
Group
Powertrain
System
EGR
Severity
Warning (MIL on)
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What P0416 means

P0416 is stored when the PCM detects a specific open-circuit fault in the Secondary Air Injection (SAI) system switching valve "B" control circuit. It is the bank "B" open-circuit counterpart to P0413 (valve A open), and provides more diagnostic precision than the generic P0415 (valve B malfunction) by identifying the fault mode as an open rather than a short.

Switching valve "B" controls the delivery of secondary air to the exhaust of the secondary cylinder bank (bank 2) on engines with dual-bank secondary air injection. When the PCM commands the valve solenoid to open and no current flows — indicating the circuit is broken — P0416 is logged. The switching valve will remain closed and no secondary air will enter the bank 2 exhaust, causing elevated cold-start emissions on that bank and a slower catalyst warm-up time.

The most commonly reported root cause in real-world repair data is a failed check valve that allows exhaust condensation or water to enter the secondary air pump, eventually causing pump seizure and consequential wiring damage. In cold climates, water freezing inside the pump and hose lines in winter is a well-documented failure pattern. An open circuit may also result from simple wiring fatigue — the solenoid harness routes near the hot exhaust manifold on many V-engine installations and is prone to heat-cracked insulation that eventually breaks conductors.

Common causes

Most-frequently reported root causes when P0416 is logged.

  • 1
    Open circuit in the switching valve "B" solenoid wiring — wire breakage, chafed harness, or heat-cracked conductor.
  • 2
    Disconnected or corroded connector at the switching valve "B" solenoid.
  • 3
    Failed solenoid with an open winding producing no current draw when commanded on.
  • 4
    Failed one-way check valve allowing water or condensation to enter the pump, causing pump seizure and consequential harness damage.
  • 5
    Frozen water inside the secondary air pump or hoses in cold weather conditions due to a defective check valve.
  • 6
    Blown fuse in the secondary air injection supply circuit.
  • 7
    Broken vacuum hose if vacuum-operated valve variant is used on certain applications.

Symptoms drivers notice

Malfunction Indicator Lamp (MIL / Check Engine Light) illuminates.
Minimal or no noticeable performance impact under warm operating conditions.
Elevated cold-start emissions on bank 2 and likely emissions test failure.
Absence of airflow noise from the bank "B" secondary air injection outlet during cold start.
Possible cold-start hesitation or rough idle on bank 2 cylinders during the warm-up phase.

How to diagnose P0416

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and confirm P0416; check for companion codes including P0415 (valve B generic), P0413 (valve A open), P0410 (SAI system), or bank 2 catalyst efficiency codes.
  2. 2
    Inspect the switching valve "B" connector and wiring harness for disconnection, broken wires, or heat damage.
  3. 3
    Test the one-way check valve on the bank "B" air injection hose — it must allow airflow in one direction only; replace if it passes air in both directions or if blocked.
  4. 4
    With the ignition on and using a scan tool actuator test to command the valve, measure voltage at the solenoid connector — battery voltage should be present when commanded on.
  5. 5
    Measure solenoid winding resistance at the valve connector; an open winding (OL) confirms the solenoid has failed.
  6. 6
    Test wiring continuity from the solenoid connector back to the PCM harness connector; locate and repair any open section.
  7. 7
    After repair, verify the MIL clears on a complete OBD drive cycle including a cold-start phase and confirm no recurrence of P0416.

Related powertrain codes

Frequently asked questions

What is the difference between P0416 and P0415?

P0415 is the generic switching valve "B" circuit malfunction code — it does not specify whether the circuit is open or shorted. P0416 refines the diagnosis to an open-circuit fault specifically, pointing toward disconnected wiring, a broken conductor, or an open solenoid winding rather than a short-circuit scenario.

Is P0416 common in cold climates?

Yes. Failed check valves are the most common root cause, and in cold climates the consequences are worse — water that enters the pump via the check valve can freeze, physically seizing the pump and cracking housings or hose connections. This creates open-circuit faults in the wiring as hoses and connectors are stressed by ice expansion. Replacing the check valve is essential to prevent recurrence.

Can I clear P0416 and pass an emissions test?

Clearing the code without repairing the fault will temporarily extinguish the MIL, but the code will return within one or two drive cycles once the PCM completes the SAI monitor. Most emissions testing stations check for recent code clears (insufficient OBD readiness monitors), so this approach typically results in a test refusal or a re-test requirement.

If P0416 appears together with P0413, is the pump failed?

Having open-circuit faults on both bank A and bank B valves simultaneously is unusual unless the wiring fault is upstream of both valves — for example, a common fuse or relay that powers both solenoids has failed, or a shared section of harness has a break. Diagnose the common supply circuit first before testing each solenoid individually.

Disabling P0416 in software

RaceTune can permanently disable P0416 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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