Secondary Air Injection System Switching Valve B Circuit Malfunction
The P0415 code means the vehicle's onboard diagnostic system has detected: Secondary Air Injection System Switching Valve B Circuit Malfunction. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $350 (parts and labor)
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What Are the Symptoms of P0415?
- Check Engine Light illuminated
- No noticeable drivability issues
- Secondary air system may not activate properly
- Failed emissions test
What Causes P0415? (Most Likely First)
- Faulty switching valve B solenoid Very High
- Open or short in switching valve B wiring High
- Corroded connector at switching valve B Moderate
- ECM driver circuit fault for valve B Low
Can I Still Drive with P0415?
Yes, but fix soon. P0415 is rated low severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.
Frequently Asked Questions
Can I drive with code P0415?
Yes. Switching valve B controls secondary air to one exhaust bank during cold starts only. Normal driving is completely unaffected.
What vehicles have two switching valves?
V6 and V8 engines often have separate switching valves for each exhaust bank. Each valve directs secondary air to its respective catalytic converter during cold starts.
Can I replace switching valve B myself?
On most vehicles, the switching valve is accessible in the engine bay. It is typically a bolt-on part with one electrical connector and one or two hose connections. Moderate DIY difficulty.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P0415?
-
Locate switching valve B -- typically on the opposite exhaust bank from valve A
-
Inspect the electrical connector for corrosion or damage
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Measure solenoid resistance and compare to specifications
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Check wiring for continuity from ECM to valve B
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Command valve B with a scan tool and verify operation
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Which Vehicles Commonly Get P0415?
- 2001-2012 BMW 530i
- 2003-2014 Audi A6
- 2004-2016 Subaru WRX
- 2002-2013 Mercedes-Benz C280
- 2005-2015 Volkswagen Touareg
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