P2392

Code

Generic P — Powertrain

Diesel Intake Air Flow B Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 27 RU: 19

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Page language: EN

Causes

Damaged or shorted wiring in the Intake Air Flow B control circuit (short to ground)
Faulty intake air flow / intake air flap actuator (Flow B) or control valve
Poor or corroded connector/terminal at actuator or PCM
Blown fuse or poor power/ground supply for the circuit
Faulty PCM/output driver (rare)
Temporary contamination or mechanical seizure of the actuator causing abnormal current draw

Symptoms

Check Engine Light / MIL illuminated
Reduced engine performance or limp home mode (if PCM limits operation)
Unusual intake air control behavior (intake flap stuck open/closed)
Possible rough idle or reduced turbo response on some systems
Stored P2392 fault and possibly related air control codes

What to check

Read and record freeze frame and live data for Intake Air Flow B values and related parameters
Visually inspect actuator, harness, and connectors for damage, corrosion, or pin back-out
Check relevant fuses and relays for continuity and proper feeding voltage
Backprobe actuator connector and measure voltage/ground with ignition ON and while commanding actuator (using scan tool)
Measure resistance of actuator winding with connector disconnected (compare to specification if available)
Perform continuity check between actuator power/ground pins and PCM connector to detect shorts to ground or opens

Signal parameters

Typical control voltage: near battery voltage when powered; "low" condition usually
Actuator coil resistance: expect a low-ohm value for motors/solenoids (often 1–50 Ω depending on actuator type) — consult OEM spec
Current draw: may be several hundred mA to multiple amps when actuator runs (use clamp meter)
Control method: direct battery voltage, switched ground, or PWM from PCM — verify with manufacturer data
Expected live-data response: commanded position should change within seconds when actuator is driven by scan tool

Diagnostic algorithm

Retrieve freeze-frame and related DTCs. Note conditions when code set (engine temp, RPM, load).
Perform visual inspection of Intake Air Flow B actuator, linkage, and wiring harness for damage, contamination, or mechanical restriction.
Check fuses/relays that feed the intake air control circuit; replace any blown fuses and retest.
With connector disconnected, measure actuator resistance. If resistance is shorted or open relative to spec, replace actuator.
Backprobe the actuator connector with ignition ON and command the actuator via a diagnostic scanner. Observe voltage/ground behaviour. If circuit voltage remains low, suspect wiring short or poor power supply.
Check continuity from actuator power/ground pins to the PCM pins. Look for short to chassis ground or high resistance/opens.
Wiggle-test wiring while monitoring signal to reproduce intermittent faults.
If wiring and actuator check good, test PCM output driver for proper switching (use oscilloscope if available). Replace PCM only after confirming external components are good and following manufacturer procedures.
Clear codes and perform a road/functional test to verify repair. Re-scan to confirm code does not return.

Likely causes

Connector corrosion or loose pin at the actuator
Wire chafing contacting body/ground resulting in a short
Failed intake air flap actuator motor or solenoid
Blown inline fuse or relay supplying actuator circuit

Fault status

⚠️ Status

PCM detected Intake Air Flow B control circuit voltage below normal threshold (circuit low). Fault stored and relevant readiness/limp strategies may be active.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours