This code indicates that the powertrain control module has detected a lower-than-expected voltage signal in the control circuit for the diesel intake air flow control actuator (often labeled "B" for a secondary bank or specific circuit). The "low" reading typically points to a short to ground, an open circuit, or an internally failed actuator that is not drawing the expected current. This system manages intake airflow for emissions control and EGR operation, and the fault prevents proper modulation of the intake throttle or swirl flap.
The electric motor or solenoid that operates the intake throttle or swirl flap has failed internally with a short to ground or open winding, causing the control circuit voltage to drop below the calibrated threshold.
The control circuit wiring has chafed against the engine block or frame, creating an unintended path to ground that pulls the voltage low before it reaches the actuator.
Moisture intrusion at the actuator or PCM connector creates high resistance or a partial short, distorting the control signal and triggering the low voltage fault.
The throttle plate or swirl flap is physically stuck due to heavy carbon buildup, preventing actuator movement and causing the control circuit to detect an abnormal electrical load.
Rarely, the transistor inside the engine computer that switches power to the actuator has failed; this should only be considered after verifying wiring and actuator integrity.
Short trips are possible but not recommended; the engine may enter limp mode with reduced power, and continued operation can lead to excessive soot accumulation in the intake.
No; despite common misdiagnosis, the root cause is almost always a faulty actuator, wiring short, or connector issue. PCM failure is rare and should only be considered after exhaustive circuit testing.
It specifically monitors the intake air flow control circuit, but because that valve regulates vacuum and flow for EGR operation, EGR-related symptoms often accompany this fault.
Clearing the code will extinguish the light temporarily, but the fault will return immediately if the circuit low condition persists, as this is a hard electrical fault.