What it means
The secondary air injection system on bank 1 delivers more flow than calibrated when the pump is commanded on - typically a stuck-open switching valve allowing free flow.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The Bank 1 secondary air injection system sends pump air into the exhaust during cold start through a switching valve and air plumbing. The engine control module monitors the system response to check that airflow stays within its calibrated range when the pump is commanded on. P2448 indicates higher than expected airflow on Bank 1, which can happen if its valve is stuck open or the pump remains powered longer than commanded.
Common causes
Most likely first.
- AIR switching valve stuck open or leaking
- Faulty AIR pump relay or control circuit keeping the pump on
- Damaged air plumbing or leaking check valve
Symptoms
- Check engine light on
- Rough idle or hesitation during cold start
- Unusual air-pump noise
- Failed emissions inspection
How to diagnose it
- Review freeze-frame and live scan-tool data to confirm the excessive-flow indication occurs during Bank 1 secondary-air operation.
- Inspect the Bank 1 switching valve, pump relay, wiring, hoses, and check valve for sticking, leaks, damage, or signs the pump is running when it should be off.
- Compare the Bank 1 pump command with its actual operation and check whether the pump stops when commanded off.
- Check the switching valve’s movement and control circuit, and verify the pump relay and wiring against the manufacturer’s specification.
- Inspect the Bank 1 air plumbing and check valve for leaks or damage that could allow unintended airflow.
Common fixes
- Free or replace a Bank 1 switching valve that is stuck open or leaking.
- Replace a faulty pump relay that keeps the pump powered.
- Repair damaged pump control wiring or connectors.
- Repair leaking or damaged Bank 1 air hoses or check valve.
Can I keep driving?
If the vehicle runs normally, limit driving to what is needed for repair; rough cold starts and an emissions test failure are possible. Stop driving if the pump makes severe noise or the engine develops significant hesitation.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.