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DTC codes / Jaguar codes / P1568

P1568 · JaguarSpeed Control Unable To Hold Speed

P1568 on a Jaguar means the engine control module (ECM) has commanded the speed control system to maintain a set speed, but the vehicle's actual speed deviated outside the allowed window for a calibrated period. The ECM monitors vehicle speed via the anti-lock braking system (ABS) wheel speed sensors and compares it to the target speed; when the difference persists, it stores this code and typically disables cruise control.

SystemPowertrain
Code typeJaguar specific
SeverityMedium
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • Cruise control disengages shortly after being set, often when climbing a hill or under light engine load.
  • The cruise control warning light or message center displays a fault, and the system may not engage at all.
  • Vehicle speed fluctuates or surges slightly while cruise is active before the system drops out.
  • Often no symptoms besides the warning light if the fault is intermittent and the system re-engages on the next drive cycle.
  • Reduced engine power or limp-home mode in some cases if the ECM interprets the speed deviation as a throttle control issue.
  • The cruise control set speed indicator may flash or turn off without driver input.

Common causes, most likely first

  1. Faulty or contaminated ABS wheel speed sensor causing erratic vehicle speed signals to the ECM.
  2. Wiring damage or corrosion in the speed signal circuit between the ABS module and the ECM.
  3. Sticking or sluggish electronic throttle body preventing smooth torque adjustments needed to hold speed.
  4. Vacuum leak or fault in the cruise control actuator diaphragm on older Jaguar models with vacuum-operated systems.
  5. Software calibration issue in the ECM or ABS module requiring a dealer-level reflash.
  6. Worn or mismatched tires causing individual wheel speed sensors to report differing speeds.
  7. Failing brake pedal position switch or clutch switch (on manual models) intermittently cancelling cruise control.

How to diagnose and fix it

  1. Road test with a scan tool recording live vehicle speed from all four wheel speed sensors to identify any dropout or inconsistency.
  2. Inspect and clean the ABS wheel speed sensors and reluctor rings for debris, cracks, or excessive air gap.
  3. Check the cruise control actuator and vacuum lines (where fitted) for leaks, splits, or a stuck diaphragm.
  4. Verify the electronic throttle body operates smoothly through its full range using a bidirectional scan tool and clean the throttle plate if carboned up.
  5. Perform a wiggle test on the speed signal wiring harness between the ABS module and ECM while monitoring live data.
  6. Check for and install any available ECM or ABS module software updates from Jaguar.
  7. Clear the code and conduct a prolonged road test at varying speeds and loads to confirm the repair before returning the vehicle.

Why P1568 is rarely a cruise control module fault

  • A common misdiagnosis is replacing the cruise control switch or module when the real cause is a single dirty ABS wheel speed sensor dropping out at certain speeds.
  • The ECM compares commanded speed to actual speed using the ABS signal, so any ABS fault code stored alongside P1568 should be addressed first.
  • On supercharged or high-performance Jaguars, a slipping belt or failing supercharger can cause actual speed to deviate from target under load, setting P1568 without any cruise control component being faulty.
  • Intermittent brake pedal switch faults can cancel cruise control and set P1568 without the driver noticing the brake lights flickering.
  • After any repair, the ECM may require a drive cycle with steady-speed cruise activation before it will clear the code permanently.

Can I keep driving with P1568?

You can usually drive the car safely with P1568 stored, but cruise control will be inoperative and the vehicle may enter reduced power mode in rare cases. Avoid using cruise control until the fault is repaired, and have the vehicle scanned promptly if the warning light is accompanied by other ABS or engine codes.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Jaguar vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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