P0415

Secondary Air Injection System Switching Valve B Circuit Malfunction

P0415 is a generic OBD-II powertrain diagnostic trouble code: Secondary Air Injection System Switching Valve B Circuit Malfunction. 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
P0415
Group
Powertrain
System
EGR
Severity
Warning (MIL on)
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What P0415 means

P0415 is stored when the PCM detects a malfunction in the Secondary Air Injection (SAI) system switching valve "B" circuit. Switching valve "B" is the counterpart to switching valve "A" and is found on engines with a dual-bank secondary air injection system — typically V6 and V8 engines where the left and right cylinder banks each have a dedicated air injection switching valve. "B" designates the secondary bank (usually the passenger-side bank on transverse V engines, or bank 2 as defined by the OBD standard).

P0415 is the generic circuit malfunction code for the "B" valve — it does not specify whether the fault is an open circuit or a short. The PCM monitors the valve solenoid circuit during commanded operation and logs the code when the measured voltage or current response does not match expectations. Common causes mirror those of its "A" counterpart (P0412): failed solenoid, wiring damage from exhaust heat, connector corrosion, or a failed check valve that allows exhaust backflow and water ingress into the system, eventually destroying the pump and associated wiring.

Because switching valve "B" controls emissions on one bank only, the engine will run normally under warm conditions. Cold-start emissions on the affected bank will be elevated, catalyst warm-up on that bank will be slower, and the MIL will be illuminated. In some twin-bank configurations the same air pump feeds both valves, so a valve "B" fault does not affect pump operation — only airflow distribution.

Common causes

Most-frequently reported root causes when P0415 is logged.

  • 1
    Faulty switching valve "B" solenoid — internal open winding or short circuit.
  • 2
    Failed one-way check valve on the bank "B" air injection line allowing condensation or exhaust backflow to damage the system.
  • 3
    Open circuit or short to ground in the switching valve "B" solenoid wiring harness.
  • 4
    Corroded, loose, or water-damaged connector at the switching valve "B" solenoid.
  • 5
    Heat damage to the wiring harness routing near the bank "B" exhaust manifold.
  • 6
    Blown fuse or faulty relay in the secondary air injection supply circuit.
  • 7
    Secondary air pump failure causing a circuit response anomaly detected at the "B" valve monitor.

Symptoms drivers notice

Malfunction Indicator Lamp (MIL / Check Engine Light) illuminates.
Hesitation or stumble during cold-start acceleration on the affected bank.
Unusual noises from the secondary air injection system at startup — buzzing, rattling, or absence of airflow sound from the bank "B" side.
Elevated cold-start emissions on bank 2 and potential emissions inspection failure.
Engine stalling at idle during the cold-start warm-up phase in some cases.
No noticeable performance issues under normal warm-engine operating conditions.

How to diagnose P0415

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and confirm P0415; check for companion codes P0410 (SAI system general), P0416 (valve B open), P0412 (valve A), or misfire codes on bank 2 cylinders.
  2. 2
    Inspect the switching valve "B" connector and wiring for corrosion, moisture, broken wires, or heat damage near the exhaust manifold.
  3. 3
    Test the one-way check valve on the bank "B" air injection hose — blow through it in both directions; it should pass air in one direction only. Replace if it allows reverse flow.
  4. 4
    Command the switching valve "B" on using the scan tool actuator test; listen for solenoid click and check for battery voltage at the solenoid connector.
  5. 5
    Measure solenoid winding resistance — compare to manufacturer specification; open (OL) or near-zero resistance indicates solenoid failure.
  6. 6
    Inspect all secondary air hoses, pipes, and fittings on the bank "B" side for blockage, cracks, or disconnection.
  7. 7
    If check valve and solenoid are serviceable but the code persists, inspect the air pump output and PCM driver circuit.

Related powertrain codes

Frequently asked questions

What is the difference between P0415 and P0412?

P0412 covers switching valve "A" — the primary bank. P0415 covers switching valve "B" — the secondary bank on dual-bank engines. Both are generic circuit malfunction codes that do not specify open vs. shorted, making them the first-level fault indicators for their respective valves.

Do all cars have a switching valve "B"?

No. Only engines with a dual-bank secondary air injection system have a "B" valve — typically V6, V8, and some V10/V12 engines. Inline 4-cylinder and inline 6-cylinder engines generally have a single secondary air path and use only valve "A". P0415 will therefore only appear on multi-bank engine configurations.

Can P0415 be caused by the air pump, not the valve?

Indirectly, yes. If the secondary air pump is seized or drawing excessive current, the abnormal electrical load can cause the PCM to detect a circuit fault at the valve control circuit on bank "B". However, the most common root cause is the check valve failing and allowing water to enter and damage the pump, which then triggers secondary wiring and solenoid faults.

Will repairing P0415 require replacing the whole secondary air pump?

Not always. If the fault is limited to the switching valve solenoid, wiring, or connector, the pump itself may be unaffected. The check valve should always be tested and replaced if faulty to prevent recurrence, as a failed check valve is a root cause of progressive secondary air injection system damage on many vehicles.

Disabling P0415 in software

RaceTune can permanently disable P0415 — 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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