P239BDiesel Intake Air Flow B Control Motor Current Range/Performance
- 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
- P239B checks the current the B-throttle motor draws while its H-bridge is switched on. A blocked or very stiff flap, a partly shorted winding or the two motor leads touching each other push the current beyond what the module expects. No manufacturer publishes P239B with values. GM's 2017 diesels set the A-motor code P02EB once more than 5.5 A is seen in 160 out of 200 evaluations while the powertrain relay delivers over 11 V; the MIL follows on the second trip. What sets it apart from P2393 is the origin of the excess current: here it comes from the load itself rather than from a lead touching battery voltage. Checking whether the flap moves freely, with the unit removed if necessary, shows whether it binds. Once the driver shuts down, the spring opens the flap; the engine keeps running with restricted EGR control.
- What you may notice
- MIL on
- Flap switched off and resting at spring position
- Often stored together with P2391 or the stuck codes
- Likely causes
- LikelyFlap blocked or very stiff, motor running at stall current
- PossiblePartly shorted motor winding
- PossibleShort between the two motor leads in harness or connector
- RareFaulty current measurement in the 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: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.