P0571 Code: Subaru Impreza (2017-2023) - Causes, Symptoms & Fixes

No recalls found in NHTSA database.

No owner complaints are listed for this exact make/model/year/issue combination in the provided data. The following guide combines the general meaning of P0571 with typical Subaru Impreza behavior and standard diagnostic practice. Data limitations: there is no specific NHTSA complaint data to quantify failure frequency for P0571 on 2017–2023 Impreza, so the guide emphasizes plausible causes, symptoms, and repairs based on widely applicable automotive knowledge.

CODE MEANING AND SEVERITY

• Code: P0571
• What it means: Cruise Control Servo Solenoid Circuit Range/Performance (often described as a problem in the cruise control servo solenoid circuit or the servo’s ability to command the throttle). In modern Subarus with electronic throttle control, this relates to the cruise control system’s actuating mechanism having an out-of-range signal or failing to respond properly.
• Severity: Mostly a convenience/comfort fault. Cruise control may not engage, may disengage, or may behave erratically. It is not typically a direct safety-critical engine fault, but losing cruise control can be inconvenient and can indicate an electrical/control-system problem that should be repaired to avoid unexpected throttle behavior under cruise control conditions. If the engine or throttle system behaves oddly outside cruise control (e.g., limp mode, throttle not responding), investigate other powertrain codes as well.

COMMON CAUSES ON SUBARU IMPREZA

• Faulty cruise control servo/actuator or its internal solenoid
  • The servo is responsible for moving the throttle to hold a set speed. If the solenoid or motor inside the servo fails or can’t actuate correctly, P0571 can be set.
• Damaged or corroded wiring/connectors in the cruise control circuit
  • Damaged insulation, pin corrosion, loose grounds, or a bad connector between the ECU/CRUISE module and the throttle body servo can create intermittent or out-of-range signals.
• Faulty or laggy electronic throttle control (ETC) wiring/communication
  • Subarus use a drive-by-wire throttle system; issues in the control data path to the throttle body can trigger P0571.
• Blown fuse or poor power supply to cruise control components
  • A fuse designated for cruise control, throttle control, or ECM/PCM power can cause intermittent or permanent loss of servo operation.
• Faulty brake or clutch switch perceptions (cancels/crashes)
  • The cruise control system uses brake/clutch switch signals to disengage. A misreading or wiring issue on these switches can indirectly affect cruise control behavior and may be associated with diagnostic codes related to cruise control behavior.
• Faulty ECU/CRUISE control module or software issue
  • A bad module or a software glitch can misinterpret signals or send incorrect commands to the servo.
• Aftermarket modifications or wiring alterations
  • Aftermarket remote starters, alarms, or performance modifications can interfere with cruise control circuits and wiring integrity.
• Low or charging-system voltage
  • Inadequate voltage can cause sensors and actuators to operate out of spec, potentially triggering P0571.

SYMPTOMS

• Cruise control fails to engage or cannot hold a set speed
• Cruise control engages but immediately disengages, or rapidly disengages and re-engages
• Intermittent cruise control operation (works sometimes, fails other times)
• Speed hold is inconsistent, or commanded throttle movement does not occur when using the set/resume buttons
• Illumination of the cruise control indicator light (symbol) on the dash, possibly alongside P0571 in the ECU.
• Other cruise control-related DTCs may appear (P0570, P0572, P0573 range-related codes)

DIAGNOSTIC STEPS

Note: This sequence prioritizes electrical problems first and progresses to actuator/component replacement if needed.

• Step 0: Safety and preparation

  • Park the vehicle on a flat surface, engage parking brake, and ensure the ignition is off when inspecting fuses.
  • Retrieve all active and historical DTCs with a scan tool. Note any freeze-frame data and related codes (especially other P0xxx codes and any vehicle speed sensor or throttle-related codes).

• Step 1: Verify the failure and collect live data

  • With engine at operating temperature, use a scan tool to:
    • Read cruise control status (on/off, engaged/disengaged).
    • Monitor throttle actuator/servo position, throttle pedal position sensor (TPS), and commanded throttle position from the cruise control system.
    • Monitor vehicle speed signal (speedometer vs. VSS).
    • Check brake switch status and any brake/ clutch input signals.
    • Check battery voltage and charging system status (should be stable around 12.5–14.8 V while running).

• Step 2: Inspect fuses and power supply

  • Look for fuses labeled for Cruise Control, Throttle Control / ETC, PCM/ECU power, and any related relays.
  • Replace any blown fuses with the correct amperage. A blown fuse is a common, inexpensive fix for intermittent P0571 symptoms.

• Step 3: Inspect wiring and connectors

  • Visually inspect the wiring harness between the cruise control module (or PCM) and the throttle body actuator/servo, including the connector at the throttle body.
  • Look for damaged insulation, frayed wires, pin bending, corrosion, or bent/loose pins.
  • Disconnect and reseat connectors; apply dielectric grease to reduce future corrosion.

• Step 4: Check brake/clutch switch circuits

  • Confirm the brake switch (and clutch switch if applicable) is functioning properly. A faulty brake switch can cause cruise control to disengage.
  • Test continuity and replace if failing. Clear the code and test cruise control behavior again.

• Step 5: Test the throttle/servo actuator

  • If your scan tool can command the throttle servo, observe whether the servo responds with a corresponding change in the throttle position when you command a set speed or throttle movement.
  • If the servo does not respond or responds with erratic movement, the servo/actuator or its wiring may be faulty.
  • Inspect the throttle body and servo mounting for external binding or mechanical interference (less common on drive-by-wire systems but worth a look).

• Step 6: Check for related or secondary DTCs

  • If there are other DTCs (e.g., P0120, P0121 for throttle/pedal position, P0500 for vehicle speed, or PCM communication codes), address those first as they may cause P0571 to appear as a secondary fault.

• Step 7: Software and calibration

  • Check for any available software updates or recalls for the vehicle that affect cruise control or ETC. If a dealer service bulletin or software update exists (not shown in the current data), applying it can fix P0571 without parts replacement.

• Step 8: Decide on repair path

  • If the servo/actuator and related wiring test as good, review the PCM/ECU health. A faulty ECU or corrupted cruise control control logic may require reprogramming or replacement.
  • If the servo or its wiring is clearly faulty, plan for replacement of the cruise control servo/actuator or throttle body assembly as needed.
  • If the issue is intermittent and not easily reproduced, consider cleaning or reseating connectors and rechecking after a set period of use.

• Step 9: Post-repair verification

  • Clear codes and perform a road test at multiple speeds to confirm the issue is resolved. Ensure the cruise control engages, holds the set speed, and disengages only when commanded (brake/pedal, or off).

RELATED CODES

• P0570 Cruise Control System Malfunction (general fault for cruise control)
• P0572, P0573 (Cruise Control Servo-related range/performance variants)
• Other throttle control or ECU-related codes (e.g., P0120, P0121, P0220) may accompany P0571 if there are broader ETC or sensor issues
• Note: These are commonly observed in the P057x family and are often seen together when the cruise control circuit has broader electrical or control issues. Always verify exact definitions with the vehicle-specific repair documentation if available.

REPAIR OPTIONS AND COSTS (2025 PRICES)

Prices are approximate and vary by region, shop rate, and whether the part is OEM or aftermarket. All estimates assume at least a basic diagnostic effort.

• Fuse replacement or minor electrical repair (wiring/connector reseating)

  • Parts: $5–$20
  • Labor: $0–$40 (DIY to professional shop time)
  • Typical total: $5–$60

• Cruise control servo/actuator replacement (often part of the throttle body assembly on Subaru ETC)

  • Parts: $150–$500 (servo/actuator or throttle-body assembly)
  • Labor: $100–$350
  • Typical total: $250–$850

• Throttle body replacement (if the servo is integrated or the throttle body itself is at fault)

  • Parts: $350–$900
  • Labor: $150–$400
  • Typical total: $500–$1,300

• Wiring harness repair or connector replacement

  • Parts: $20–$150
  • Labor: $100–$300
  • Typical total: $120–$450

• ECU/PCM reprogramming or replacement

  • Parts: $0–$900 (depends on whether a reman or new ECU is used)
  • Labor: $100–$300
  • Typical total: $100–$1,200

• Dealer vs independent shop

  • Dealer services tend to be more expensive but may be necessary for specific software updates or module reseating/recalibration. Independent shops can often diagnose and repair ECU wiring or servo issues at lower labor rates.

DIY vs PROFESSIONAL

• Do-it-yourself (DIY) suitability
  • Suitable for: basic fuse checks, inspecting and reseating electrical connectors, cleaning corroded connectors, checking obvious wiring damage, and performing simple tests with a scan tool to observe live data if you have the necessary know-how.
  • Not recommended for: replacing the throttle body or cruise control servo without understanding ETC systems, or if the issue appears to be a PCM/ECU fault or complex wiring harness failure. Drive-by-wire throttle systems involve high electrical power and precise control logic; improper handling can create safety concerns.
• When to seek a professional
  • If cruise control cannot be reliably engaged or held, or if multiple DTCs are present.
  • If the issue persists after checking fuses, wiring/connectors, and brake/clutch switches.
  • If the servo, throttle body assembly, or PCM software updates are needed.
  • If you lack the specialized diagnostic tools to command the throttle and read live actuator data.

7. PREVENTION

• Maintain stable electrical systems
  • Keep the battery and charging system healthy; a failing alternator or battery can cause subtle ECU/actuator communication issues that trigger P0571.
• Regular maintenance on ETC components
  • Periodic inspection of connectors around the throttle body, cruise control module, and related harnesses can prevent corrosion-related faults.
• Avoid aggressive aftermarket modifications
  • Aftermarket wiring, alarm, or remote-start systems can interfere with cruise control circuits. If added, ensure proper integration with the factory ECU and proper shielding/diode isolation where required.
• Software updates
  • Stay current with any Subaru firmware or ECU software updates that relate to cruise control or ETC. Dealer or authorized shop can confirm availability.
• Safe operation practices
  • Use cruise control prudently in wet/icy conditions or heavy traffic to reduce electrical/actuator stress and potential transients.

Important data note

• The provided NHTSA data for this exact vehicle and issue shows no owner complaints and no recalls. This limits the ability to quote real-world failure frequency or documented investigations. The diagnostic approach above emphasizes generic, broadly applicable procedures and Subaru-specific considerations when diagnosing P0571 on a 2017–2023 Impreza.