What it means
The control module detects that diesel intake air flow B control performance does not meet the expected response.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The diesel intake air flow B actuator moves valve B to regulate intake airflow for functions such as EGR mixing. The control module sets this code when valve B’s response does not match the expected movement, even if the circuit is not electrically open.
Common causes
Most likely first.
- Intake air flow control valve sticking from soot or deposits
- Actuator or linkage fault
- Position sensor or wiring fault
Symptoms
- Check-engine light on
- Reduced engine power or sluggish acceleration
- Rough idle or stalling
How to diagnose it
- Record freeze-frame data and compare live commanded and actual positions for intake air flow valve B while the fault is present.
- Inspect valve B, its linkage, and nearby intake passages for soot or deposits that could restrict movement.
- Check the actuator connector, position-sensor wiring, and linkage for looseness, wear, or damage.
- Use the manufacturer’s scan-tool procedure to command valve B through its range and watch whether the position changes smoothly and follows the command.
- If movement is restricted or feedback is inconsistent, test the actuator and position-sensor circuit against the manufacturer’s specification.
Common fixes
- Clean soot or deposits from valve B using the approved service procedure.
- Repair or replace a sticking or damaged valve B linkage.
- Repair damaged wiring or poor connector contacts at the actuator or position sensor.
- Replace a failed actuator or position sensor if testing confirms the fault.
Can I keep driving?
Reduced power, rough idle, or stalling can make the vehicle unreliable in traffic. Avoid demanding acceleration, and stop driving if it stalls or cannot maintain safe speed.
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.