Secondary Air Injection System Relay A Circuit Malfunction
There's a problem with the relay for the secondary air injection system.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The secondary air injection system helps reduce emissions by injecting fresh air into the exhaust during cold starts. When the system isn't working right, it can’t blow in that extra air, so your car might pollute more than it should.
What the computer is actually seeing
The engine control module (ECM) expects a specific voltage signal from the secondary air injection relay circuit, usually around 12 volts when activated. If it sees 0 volts or fluctuating voltage outside expected range, it triggers the P0415 code.
What a healthy reading looks like
Voltage at the secondary air injection relay should be around 12 volts when activated, and continuity should be present in the circuit when the relay engages.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check the wiring and connectors for the secondary air injection relay for damage, corrosion, or loose connections. Fix any issues found.
- 2Using a multimeter, check for voltage at the relay while the engine is running. You should see around 12 volts when the secondary air system is activated. If not, check the fuse.
- 3With the engine running and the system activated, check for continuity in the wiring to the secondary air injection pump. If there's no continuity, trace the wiring for open circuits.
- 4If the relay has 12 volts but the pump isn't running, replace the secondary air injection relay and retest.
Common causes
- Faulty secondary air injection relay
- Wiring issue in the relay circuit
- Faulty ECM
- Blown fuse in the secondary air injection circuit
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Is it safe to drive with P0415?
Yes, it's generally safe to drive, but emissions may be higher and it can affect performance.
Will this code come back after clearing?
If the underlying issue isn't fixed, the code will likely return.
What happens if I ignore this code?
Ignoring it could lead to increased emissions, failing an emissions test, and potentially contribute to engine components getting damaged over time.
Working a real vehicle right now?
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