P239CDiesel Intake Air Flow B Control System - High Air Flow Detected
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P239C belongs to the air-mass control loop rather than to the throttle alone: with the B intake throttle taking part in that control, the module sees more fresh air than its target and cannot bring the reading down even at the limit of its authority. Too little recirculated exhaust gas is both the usual cause and the consequence, from an EGR valve stuck shut, a blocked EGR cooler, a flap that cannot close or an air-mass meter reading high. No manufacturer was found that uses P239C. Ford's 2023 diesels run this test for their single intake throttle under P02EC, comparing desired and measured air mass against a speed/torque map; the 6.7 L needs 10 s, the 3.0 L 5 s. NOx emissions rise; driveability normally stays unchanged.
- What you may notice
- MIL on
- No noticeable driving change in most cases
- Often stored together with EGR flow codes
- Likely causes
- LikelyEGR valve stuck closed or EGR cooler clogged
- PossibleB throttle unable to close far enough
- PossibleAir-mass meter reading too high
- RareBoost higher than intended
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.