P2390 code meaning
Diesel Intake Air Flow B Control Circuit/Open
Powertrain system Generic code P23xx codes Check engine light
What P2390 means
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.
P2390 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P2390
- 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
Common causes of P2390
- Most 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
- Less likelyFaulty output stage in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Diesel intake throttle valveThrottle valve motorActuator wiring
What each part of P2390 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 90 | The exact fault in that area. |
What to do next
- Note P2390 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2390
What does P2390 mean?
P2390 means "Diesel Intake Air Flow B Control Circuit/Open". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P2390?
Drive gently and only to a workshop. With P2390 the car can go into limp mode (reduced power) to protect itself.
Will P2390 fail an emissions test?
Yes, it can. P2390 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2390 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2390 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.