Secondary Air Injection System Flow Switch Failure
The secondary air injection system is not operating properly due to a flow switch issue.
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)
Your car’s computer isn’t getting the right signal from a switch that monitors airflow in the secondary air injection system, which helps reduce emissions during startup.
What the computer is actually seeing
The computer expects to see a signal from the flow switch indicating proper air flow in the secondary air injection system, typically between 0.5 to 5 volts for an active switch. If it detects a voltage outside of expected parameters, it will trigger this code.
What a healthy reading looks like
Flow switch voltage should read between 0.5 to 5 volts when the secondary air injection is active. The system should activate within 5 seconds after starting the engine during cold start conditions.
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.
- 1Start with a visual inspection of wiring and connectors related to the secondary air injection system for damage or corrosion. Connectors should be clean and tight.
- 2Check the operation of the secondary air pump by listening for it to run when the engine is cold and the key is turned on. You should hear it for about 30 seconds to 1 minute.
- 3Use a scan tool to check the voltage at the flow switch while the secondary air pump is running. It should read between 0.5 to 5 volts. If not, replace the flow switch.
- 4Inspect air passages for blockages, such as carbon build-up or obstructions. Ensure that air can flow freely to and from the secondary air injection system.
Common causes
- Failed secondary air injection flow switch
- Blocked air passages in the secondary air system
- Electrical issues such as damaged wiring or poor connections
- Faulty secondary air pump
- Vacuum leaks affecting the operation of the air injection system
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but you may experience increased emissions and may fail emissions tests.
Will this code come back after clearing it?
It may come back if the underlying issue is not resolved.
Why does this code sometimes pair with P0410?
Both codes relate to the secondary air injection system; P0410 indicates the system is malfunctioning while P2431 specifies a flow switch issue.
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