What it means
With diesel intake air flow valve B commanded closed the measured airflow is above the calibrated threshold - valve does not seat or position sensor offset.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Diesel intake air flow valve B regulates airflow through its part of the intake system. The control module compares measured airflow with the expected result when it commands valve B closed; this code sets when airflow remains too high, for example because the valve does not seat or its position reading is inaccurate.
Common causes
Most likely first.
- Valve not seating fully
- Carbon or debris preventing closure
- Linkage, actuator, or position sensor fault
Symptoms
- Check-engine light on
- Reduced engine power or sluggish acceleration
- Rough idle
How to diagnose it
- Check freeze-frame data and live airflow and valve-position readings to confirm the fault occurs when valve B is commanded closed.
- Inspect valve B, its linkage, and the nearby intake passage for carbon or debris that could prevent full closure.
- Use a scan tool to command valve B through its range and compare indicated position with observed movement.
- Inspect the B actuator and position-sensor connector and wiring for damage, poor contact, or signs of water ingress.
- If the valve moves freely and the circuit checks out, compare airflow and position readings with the manufacturer's specification to isolate a sensor offset or actuator fault.
Common fixes
- Clean carbon or debris from valve B and its seating area if the manufacturer's service procedure permits.
- Repair or free a sticking linkage that prevents valve B from closing.
- Repair loose, damaged, or corroded wiring and connectors at the B actuator or position sensor.
- Replace the faulty B actuator, position sensor, or valve assembly identified by testing.
Can I keep driving?
If the engine is running smoothly, a short drive may be possible, but avoid hard acceleration if power is reduced or idle is rough. Incorrect intake-air control can worsen drivability and emissions.
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.