P24DDReductant Purge Control Valve B Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P24DD means the control line of purge valve B shows too little voltage at a moment when it should be high. With the low-side switching that GM uses for valve A, this is checked while the driver is off: the line should then carry battery voltage through the coil, and a low reading indicates a short to ground between valve and controller, so the valve may sit energised permanently. No manufacturer documents P24DD publicly; The valve A counterpart, P20A2, appears in GM's diesel tables for the 6.6 L engine. CARB's heavy-duty rules require detection of such circuit faults on SCR actuators. Typical spots are chafed wires near the tank and a coil that shorts to its housing. The opposite case is P24DE, an interruption P24DB.
- What you may notice
- Malfunction indicator lamp on
- Valve may remain in purge position, dosing pressure not reached
- Likely causes
- LikelyControl wire chafed to ground near tank or frame
- PossibleValve coil shorted to its housing
- RareWater or DEF in the connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.