P24DC

Code

Generic P — Powertrain

Reductant Purge Control Valve B Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 16 EN: 22 RU: 11

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Page language: EN

Causes

Faulty reductant purge control valve B (stuck, mechanically failed or electrically open/short)
Wiring fault or poor connector (open, short to ground/power, high resistance, corrosion)
Clogged or restricted reductant lines, filters or valve ports (crystallized/contaminated DEF)
Insufficient system voltage or poor ground
Faulty reductant pump or pressure supply affecting purge function
Control module (PCM/ECU) or software fault

Symptoms

MIL (check engine) lamp illuminated
Reduced SCR/aftertreatment performance and possible increased NOx emissions
Regeneration or dosing warnings on dash (manufacturer dependent)
Audible absence of expected valve click when commanded
Possible drivability unaffected, or limp/limited engine strategies when emissions limits exceeded

What to check

Read freeze frame and live data with a scan tool; note valve B commanded state and actual feedback (if available)
Attempt to actuate/pulse purge valve B from the scan tool and listen/feel for operation
Visually inspect harness and connector for corrosion, damage, loose pins or contamination
Measure connector terminal voltage when valve is commanded ON and OFF (backprobe) and compare to spec
Measure coil resistance of the purge valve (engine off, disconnected) and compare to service specification
Perform wiggle test on harness while monitoring signal for intermittent changes

Signal parameters

Command voltage: typically a switched ground or 5–12 V supply depending on vehicle — check service manual for exact method
Coil resistance: varies by OEM; commonly low tens of ohms. Verify actual spec in repair manual before replacing
Duty cycle/current draw when modulated: check manufacturer values; abnormal high/low current indicates coil or supply issue
Response feedback (if equipped): valve open/closed status or pressure/flow sensor readings should change when commanded

Diagnostic algorithm

Connect a capable scan tool. Confirm DTC P24DC, record freeze frame and live data for purge valve B.
Use the scan tool to command purge valve B on/off while monitoring live data and listening for valve activation (click). Note any absence of response.
Visually inspect the valve connector and harness for corrosion, loose pins, damage, or contamination. Repair as needed.
With ignition off, disconnect valve and measure coil resistance across the valve terminals. Compare to manufacturer specification. Replace valve if out of range or open/short.
With connector connected, backprobe the control and power terminals. Command valve on and measure voltage/duty cycle and current draw. Verify proper supply and switching to ground. Repair wiring or supply faults.
Inspect reductant lines, filters and valve ports for restriction or crystallized DEF. Clean or replace clogged components and flush lines if contamination is found.
If electrical and flow checks pass, verify reductant pump operation and system pressure/flow sensors. Repair or replace defective components.
If all components and wiring test good, consider reprogramming or replacement of the control module only after confirming no other faults and following manufacturer procedures.
Clear DTCs and perform verification drive or actuation tests to confirm the fault does not return.

Likely causes

Solenoid coil inside purge valve B has failed (open or shorted)
Connector terminals corroded or pin pushed out causing intermittent contact
DEF crystallization blocking valve movement or lines
Damaged harness from heat or road debris causing intermittent short
Low DEF level or contaminated DEF preventing proper purge operation

Fault status

⚠️ Status

P24DC — Reductant Purge Control Valve B Performance. The engine control module detected that Purge Valve B is not performing within expected parameters (electrical response or flow/pressure feedback) when commanded. This can indicate a failed valve, wiring issue, restriction, poor reductant quality, or module problem.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours