P24DD

Code

Generic P — Powertrain

Reductant Purge Control Valve B Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 17 EN: 31 RU: 21

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Page language: EN

Causes

Short to ground in the purge valve B control wiring
Open or high-resistance connection (damaged wiring, corroded connector pins)
Blown fuse or faulty relay supplying the purge valve circuit
Faulty purge control valve (internal short or open coil)
Poor or missing ground at valve or ECU
Low battery/weak charging system during test

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced or disabled reductant/urea purge operation
Failed emissions readiness or failed emissions test
Possible stored related reductant/urea system faults
Occasional difficulty with selective catalytic reduction (SCR) performance or elevated NOx

What to check

Scan for current and pending codes and view freeze frame and live data
Verify battery voltage is within specification and charging system is healthy
Visually inspect harness, connectors and seals at purge valve B for damage or corrosion
Backprobe the purge valve connector and operate the purge command with a scan tool while measuring voltage
Measure coil resistance of the purge valve with ignition off
Check for continuity to ECU and check for short to ground in the control wire

Signal parameters

Resting control circuit voltage when valve not commanded: ~0 V (or near ground)
Commanded ON voltage: approximately battery voltage or a PWM signal (typically up to ~12 V depending on system)
Typical solenoid coil resistance (generic): ~10–40 ohms (varies by manufacturer); consult OEM spec
Expected current draw when energized: commonly 0.2–2 A depending on coil design
PWM control: duty cycle varies with command; frequency often in the tens to low hundreds of Hz (refer to OEM)

Diagnostic algorithm

Retrieve all related DTCs and freeze-frame data with a capable scan tool; note conditions when code set.
Verify system voltage: ensure battery and charging system voltage are within specification before testing.
Visually inspect the purge valve B connector and wiring for corrosion, pin push-out, damage or chafing.
With ignition ON (engine off), measure the purge valve coil resistance at the valve connector; compare to OEM spec. An open or shorted coil indicates a bad valve.
Backprobe the control wire at the valve connector. Command the purge valve ON with a scan tool while monitoring voltage. If the ECU commands but voltage is low or absent, suspect wiring/fuse/ECM.
If low voltage is present, test for short to ground: disconnect the valve and measure resistance from control wire to ground. Low resistance indicates a short to ground.
Check supply fuse/relay and any intermediate power/ground paths required for the valve; replace if faulty.
Inspect continuity from the valve connector to the ECM driver pin. Repair any open/high-resistance sections.
If wiring and valve check good, consider replacing the purge valve. If issue persists with correct wiring and a known-good valve, suspect ECM output driver and refer to OEM procedures for ECM testing/repair.
After repair, clear codes and perform a drive cycle or regeneration as required to verify the fault does not return.

Likely causes

Damaged connector or corroded terminal at purge valve B
Chafed wiring harness contacting chassis ground (short to ground)
Failed purge valve solenoid coil showing very low/zero expected voltage under command
Blown inline fuse or failed relay feeding the valve circuit
ECM output stage failed (less common)

Fault status

⚠️ Status

Reductant Purge Control Valve B Circuit Low — low voltage detected on the purge valve B control circuit (possible short to ground, open circuit, or faulty valve/ECM).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours