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Home / DTC / P0651 — Pressure regulator and solenoid supply

P0651 — Pressure regulator and solenoid supply

Detailed page for trouble code P0651.

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Code

P0651

LAND ROVER P — Powertrain

Pressure regulator and solenoid supply

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 9 EN: 18 RU: 36
AI status
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Page language: EN

Causes

  • Blown or faulty fuse or relay supplying the pressure regulator/solenoid
  • Poor battery condition or low system voltage
  • Open, short to ground or short to battery in wiring or damaged connector
  • Corroded or loose connector pins at the solenoid/regulator or ECU
  • High resistance in supply/ground circuit (poor crimp, corrosion)
  • Faulty pressure regulator or solenoid (internal open/short)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Reduced engine power or limp-home mode (depending on system)
  • Poor boost/pressure control, turbo or fuel pressure issues
  • Hard starting, stalling or rough idle in some cases
  • Stored fault(s) relating to regulator/solenoid performance

What to check

  • Read all stored and pending codes and freeze-frame data with a scan tool
  • Visually inspect wiring harness, connectors and pins for damage or corrosion
  • Check relevant fuse(s) and relay(s); replace if blown or suspect
  • Measure battery voltage and charging system condition
  • Backprobe supply and ground pins at solenoid/regulator connector with ignition ON and engine running
  • Measure resistance of the solenoid/regulator coil with connector disconnected

Signal parameters

  • Supply voltage at solenoid/regulator supply pin (Ignition ON): approx. 11–14.5 V (battery voltage)
  • Voltage drop between battery positive and solenoid supply under load: should be minimal (
  • Ground continuity from solenoid ground to chassis/ECM ground: near 0 ohms
  • Typical coil/resistor resistance (consult vehicle spec): commonly in the range of ~5–30 ohms — reference factory specification before replacement
  • Control signal to regulator/solenoid (if PWM controlled): variable duty cycle 0–100% depending on operating conditions

Diagnostic algorithm

  1. Verify the code P0651 with a scanner, record freeze-frame data and clear codes to see if it returns.
  2. Inspect battery, main fuses and any dedicated fuse/relay for the pressure regulator/solenoid circuit; replace suspect items and retest.
  3. Visually inspect connectors and wiring from fuse/relay/ECM to the pressure regulator/solenoid for damage, corrosion or rodent chew.
  4. With ignition ON (engine off), backprobe the supply pin at the solenoid/regulator connector and confirm battery voltage is present. If no voltage, trace back to fuse/relay/ECM.
  5. Check ground continuity from the solenoid/regulator ground pin to chassis/ECM ground; repair poor ground connections.
  6. Disconnect the solenoid/regulator and measure coil resistance; compare to factory spec. An open or shorted coil indicates component replacement.
  7. With connector connected, monitor the supply and control signal while cranking/idle with a lab scope or multimeter (voltage and PWM duty). Look for intermittent loss or abnormal values.
  8. Perform wiggle tests on harness and connectors while monitoring signals/codes to locate intermittent faults.
  9. If wiring, connectors, fuse and component test good, consider ECM driver fault; consult manufacturer diagnostic procedures before replacing ECM.
  10. After repairs, clear codes and perform test drive to confirm P0651 does not return and related system operates correctly.

Likely causes

  • Blown fuse or failed relay in the regulator/solenoid supply
  • Open or shorted wiring between fuse/relay and solenoid/regulator
  • Corroded/loose connector at solenoid or ECM causing voltage drop
  • Failed pressure regulator/solenoid coil (open/high resistance)
  • Intermittent battery/ground connection causing low supply voltage

Fault status

⚠️ Status
Supply circuit for pressure regulator/solenoid reporting open/low/high-resistance condition; MIL set.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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