Secondary Air Injection System Relay A Circuit Low
There’s a problem in the secondary air injection system relay A circuit.
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 car uses a secondary air injection system to help reduce emissions. If it can't activate properly, it won't add air to the exhaust and you're likely looking at pollution controls not working right.
What the computer is actually seeing
The PCM looks for a specific voltage from the secondary air injection relay. When the relay is supposed to activate, the voltage should be around 12V; if it sees below 2V, it triggers this code.
What a healthy reading looks like
Relay should send around 12V during activation and under 1 ohm resistance when tested.
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.
- 11. Check battery voltage; should be 12V or more. If low, charge or replace battery.
- 22. Inspect the wiring and connectors between the PCM and the secondary air injection relay for damage or corrosion.
- 33. Test the secondary air injection relay with a multimeter; it should not exceed 1 ohm of resistance when it's activated.
- 44. If the relay checks out, activate the secondary air injection pump; you should see 12V at the pump connector. If not, replace the relay.
- 55. If the pump does not activate, check the power and ground at the pump. Repair any wiring issues.
- 66. If all checks out but the code persists, suspect a faulty PCM.
Common causes
- Faulty secondary air injection relay
- Wiring issues or corroded connectors
- Faulty secondary air injection pump
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It’s drivable, but you may have increased emissions and could fail an emissions test.
Will this code come back after clearing?
If the underlying issue isn’t fixed, yes, the code will likely return.
Why does this pair with P0416 or P0418?
These codes all relate to the secondary air injection system, indicating problems with various components or circuits within that system.
Working a real vehicle right now?
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