P0415
Secondary Air Injection System Switching Valve A Circuit Shorted
Powertrain Emission Controls Secondary Air Injection 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The secondary air injection valve that helps reduce emissions is electrically shorted, preventing it from opening and closing properly. Think of it like a stuck electric switch that won't flip on and off correctly.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Failed emissions test or high HC/CO readings
Rough idle or hesitation during cold start
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the voltage and current draw of the secondary air injection (SAI) switching valve solenoid. It expects specific resistance and switching patterns; a short circuit creates abnormal current flow that exceeds safe thresholds, triggering the fault code.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Solenoid Coil Resistance 4-14 ohms depending on design Below 2 ohms or open circuit (infinite ohms)
Circuit Voltage Drop 12V supply with controlled ground Continuous low voltage or short-to-ground detected
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness and connectors
Inspect connector terminals for corrosion, bent pins, or moisture; clean with electrical contact cleaner and reseat connections.
2
Secondary Air Injection solenoid valve
Test solenoid resistance with a multimeter; if reading is below 2 ohms or infinite, replace the valve assembly.
3
Engine control module (ECM) wiring
Check for pinched, damaged, or shorted wires in the SAI circuit harness running from ECM to valve; repair or replace damaged sections.