Powertrain, generic (extended)

P2392 Diesel Intake Air Flow B Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2392 is set when the module finds the motor output for the B intake throttle pulled towards ground, for example by a chafed wire touching the engine, water inside the connector or a shorted motor. The output stage protects itself and switches off. No manufacturer documents P2392 publicly. Ford's 2023 diesel summary checks the matching A-valve fault (P02E2) continuously while the power stage is active and needs only 0.2 s to register it. Because an H-bridge drives the motor, a ground short on either motor lead can be the trigger; whether the code points to one particular lead depends on the maker. With the motor dead the flap returns to its spring position, open on most designs: driveability changes little, but the EGR rate drops and the module may refuse to regenerate the particulate filter.

Likely causes

Motor lead chafed through and touching engine or body ground
Water or corrosion in the throttle connector
Internal short of the throttle motor to its housing
Damaged H-bridge in the engine control module

Symptoms

  • MIL on, code returns immediately after clearing
  • Regeneration blocked or aborted
  • Little or no change in driving

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–500
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

diesel intake throttle valvethrottle valve motoractuator wiring

Related codes

P2393P2390P239BP02E2

References: law.cornell.edu, fordservicecontent.com, ms-motorservice.com.