What it means
A fault has been detected in AIR System B. The code does not specify that oxygen-sensor lean response is the detection method.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
AIR System B is the secondary air injection system identified as B by the vehicle's diagnostic strategy; it pumps fresh air into the exhaust during specified operating conditions to support emissions control. This code indicates a fault in that system, but does not specify that the module detected it through oxygen-sensor response.
Common causes
Most likely first.
- Failed AIR pump motor or impeller
- Check valve seized by exhaust soot
- Corroded or cracked air injection pipe
Symptoms
- Check-engine light may illuminate
- Reduced engine performance
How to diagnose it
- Save freeze-frame data and check for related AIR pump, valve, or flow codes to understand when AIR System B was expected to operate.
- Inspect the AIR System B pump, hoses, and air injection pipe for cracks, corrosion, loose fittings, or signs of exhaust soot.
- Check whether the pump runs when commanded using a suitable scan tool and listen for abnormal noise that could indicate a failed motor or impeller.
- Inspect the System B check valve for sticking or soot buildup, and make sure it prevents exhaust from flowing back toward the pump.
- Test the pump's electrical supply and control circuit, then assess pump output and pipe flow using the manufacturer's procedure.
Common fixes
- Repair a cracked or corroded AIR System B injection pipe or hose.
- Clean or replace a check valve seized by exhaust soot.
- Repair a loose or corroded pump connector or its wiring.
- Replace the AIR System B pump if its motor or impeller fails the specified test.
Can I keep driving?
If the engine runs normally, short trips may be possible, but the emissions fault can persist and performance may decline. Avoid driving if the engine begins running roughly or loses power enough to make traffic unsafe.
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.