Powertrain, generic (extended)

P2390 Diesel Intake Air Flow B Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2390 concerns the drive circuit of the second electronically operated intake throttle that some diesel engines carry; which flap a maker labels A or B is its own choice. With the driver switched off, the engine module checks whether the motor circuit is closed; an open wire, a pulled connector or a burnt motor winding sets this code. No manufacturer publishes P2390 with thresholds. For the A valve (P02E0) GM's 2017 diesel tables look for a load resistance above 200 kΩ in 160 of 200 checks at 12.5 ms, provided the relay feeds more than 11 V, as a two-trip fault. A dead motor leaves the return spring to hold the flap open on most designs, so the vehicle drives normally while EGR control and regeneration heating lose authority.

Likely causes

Connector at the B throttle unplugged, loose or with pushed-back terminals
Broken motor lead in the harness between module and throttle
Open motor winding inside the throttle unit
Faulty output stage in the engine control module

Symptoms

  • MIL on, often without a noticeable change in driving
  • Particulate filter regeneration delayed or blocked
  • Engine may shake more when switched off because the flap no longer closes

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

P2392P2393P239BP2391P02E0

References: law.cornell.edu, gsi.ext.gm.com, ms-motorservice.com.