P2394Diesel Intake Air Flow B Control Stuck Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2394 means the B intake throttle remains wider open than requested even though the module drives its motor hard towards closing. A flap that cannot throttle fails to create the manifold depression that strong exhaust recirculation and regeneration heating depend on. No manufacturer documents P2394 openly. GM's 2017 diesel tables catch the A-valve version (P02E4) when the setpoint-minus-actual error is below -16 % while the duty cycle is beyond -34 %, in 1,280 of 1,600 samples at 6.25 ms, lighting the MIL at once; Ford's 2023 diesels use a deviation of more than 15 % held for 25 s. Coking, a broken gear tooth or a seized shaft are the usual reasons. Driving feels normal, but NOx and the soot load rise.
- What you may notice
- MIL on
- Frequent or failing particulate filter regenerations
- Engine shakes when switched off
- Likely causes
- LikelyDeposits holding the flap in an open position
- PossibleBroken gear tooth or stripped drive between motor and shaft
- PossibleMotor too weak to overcome the return spring
- RareForeign object or broken part blocking the flap
- 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: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.