What it means
The control module detected a low electrical signal in the diesel intake air flow control circuit.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The diesel intake air flow control system adjusts airflow into the engine, and this code indicates that the control module sees a low electrical signal in the circuit. Its low-signal designation is electrical; carbon buildup or a stuck flap may cause a separate airflow problem and should be checked rather than assumed to be the cause.
Common causes
Most likely first.
- Carbon buildup holds flap closed
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
Symptoms
- Check-engine light on
- Reduced engine power or sluggish acceleration
- Rough idle or stalling
- Increased fuel consumption
How to diagnose it
- Save freeze-frame data and review available actuator command and position data to see when the low-signal fault occurred and whether the valve responded.
- Inspect the actuator connector and harness for corrosion, loose terminals, rubbed insulation, or a signal wire shorted to ground.
- With the engine off, inspect the valve and intake passage for carbon or debris that could hold the flap closed, without forcing the mechanism.
- Using the manufacturer’s wiring diagram, test for a short to ground, poor terminal contact, and circuit continuity.
- If wiring is sound, test the actuator and position feedback according to the manufacturer’s procedure.
Common fixes
- Repair a shorted or chafed signal wire and secure the harness.
- Clean and secure corroded or loose connector terminals.
- Clean carbon or debris that prevents the flap from moving, using the approved procedure.
- Replace the actuator or repair the valve mechanism if testing confirms it is faulty.
Can I keep driving?
Because this fault may trigger reduced-power operation and can cause rough running or stalling, avoid long trips, heavy loads, and high-speed roads. Stop if the engine stalls or cannot maintain safe speed, and have the intake fault diagnosed promptly.
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.