P2448: Secondary Air Injection System High Air Flow Bank 1
What to do
A hum from the air pump that continues well after a cold start is the audible version of this code. Have the relay and switching valve checked before either the pump or any lean-code diagnosis is paid for — the P2440 chain of consequences starts here.
What this code means
The secondary air system is flowing more air than commanded — the family's least intuitive complaint, because most of its codes are about air failing to arrive.
High flow means something is running or open when it should not: a relay stuck feeding the pump, or the switching valve failed open so the pump's air keeps entering the exhaust past its scheduled shut-off. That second version is P2440's fault seen from the flow side — and it inherits P2440's consequence, the one that makes this family matter: air pumped past the oxygen sensors reads as a lean mixture that does not exist, and the module over-fuels an engine with nothing wrong. Continuous flow also keeps a pump built for cold-start bursts running far beyond its duty cycle, which is how the pump becomes the second casualty.
Likely causes
Start here
- Faulty secondary air injection relay · easy
- Faulty secondary air switching valve · moderate
Rare
- Failed control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P2448.