P2390Diesel Intake Air Flow B Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- 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
- Likely causes
- LikelyConnector at the B throttle unplugged, loose or with pushed-back terminals
- PossibleBroken motor lead in the harness between module and throttle
- PossibleOpen motor winding inside the throttle unit
- RareFaulty output stage in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.