No recalls found in NHTSA database
No NHTSA owner complaints are listed for the Subaru Impreza (2017–2023) tied to P0715 in the provided data. This means there is limited model-year–specific complaint data to base severity or frequency on. The diagnostic guide below uses general automotive knowledge plus typical Subaru CVT behavior to help you diagnose P0715 on a 2017–2023 Subaru Impreza. Prices listed are approximate 2025 market ranges and can vary by region and shop.
CODE MEANING AND SEVERITY
What P0715 means: P0715 is the OBD-II code for “Input/Turbine Speed Sensor Circuit Malfunction.” In a CVT-equipped Subaru Impreza, this typically refers to the input speed sensor (ISS) circuit that monitors the transmission input shaft speed. Some manufacturers also call this the turbine speed sensor in reference to the turbine/impeller in the transmission.
Why it matters: The transmission control module (TCM) uses the input speed signal to manage shifting strategy, gear/ratio changes, and overall transmission behavior. If the signal is erratic, missing, or out of range, the TCM may command improper shifts or enter a failsafe/limp mode to protect the transmission.
Severity in practical terms:
- Moderate to high potential for drivability issues: harsh shifting, slipping, delayed or harsh engagement, or no-shift conditions.
- Possible transmission limp mode if the TCM detects a persistent fault.
- Not typically an immediate safety hazard, but driving with a faulty ISS can cause further transmission wear or damage if left unaddressed.
Data limitations: Based on the provided data, there are no recorded complaints or recalls for this code on this specific model range. That means no model-specific frequency or verified common-fix statistics are available from NHTSA in the given dataset. Diagnosis should still follow sound automotive diagnostic practices.
COMMON CAUSES ON SUBARU IMPREZA
Faulty input speed sensor (ISS) or turbine speed sensor: Sensor failure, degraded signal, or wrong resistance values.
Damaged or corroded wiring or connectors: Chafed, cracked insulation, water intrusion, bent or pushed pins at the sensor connector or the TCM/ECU connector.
Poor or intermittent grounds: A bad ground on the sensor circuit or TCM can produce fluctuating signals.
Electrical faults in the control module: A software fault or failing TCM/ECU/TCU (transmission control unit) that misreads or misinterprets the sensor signal.
Faulty CVT fluid or internal CVT issues (less common as a root cause of P0715, but fluid condition or debris can affect sensing or data integrity indirectly): very dirty or burnt CVT fluid can cause abnormal transmission behavior that might trigger a fault condition or masking of a sensor issue.
Sensor installation or mounting issues: Sensor not seated properly after service, or mounting gasket/o-ring leaks altering the sensor environment.
Wiring routing issues unique to Subaru drivetrain layouts: Harness rubbing near exhaust shields or moving parts can cause intermittent faults.
SYMPTOMS YOU MAY NOTICE
Check Engine Light (CEL) or transmission warning light on.
Harsh, delayed, or irregular shifting; slipping between gears or CVT “rubber-band” feel.
Limp mode or reduced engine/transmission performance to protect the drivetrain.
Diminished acceleration or a mismatch between engine RPM and vehicle speed.
Intermittent or persistent transmission “no shift” condition where the vehicle won’t shift properly.
In some cases, the car may drive normally after a reset, then re-enter P0715 later if the underlying issue recurs.
DIAGNOSTIC STEPS
Note: Work safely with the vehicle on a level surface, in park or neutral with the parking brake set as appropriate. A professional scan tool capable of live data is very helpful.
Step 1: Confirm and contextualize the code
- Use a capable OBD-II scanner to confirm P0715 and pull freeze-frame data.
- Note the engine RPM, vehicle speed, gear (PRNDL) state, and any other stored codes (P0700, P0710, P0711, P0712, etc.).
- Check for any transmission temperature or fault-tracing data available in the vehicle’s data stream.
Step 2: Inspect obvious electrical and mechanicals
- Visually inspect the transmission area for damaged wiring, loose connectors, or signs of water intrusion.
- Check the ISS/turbine sensor connector for corrosion, bent pins, or loose seating. Do not force pins; replace if damaged.
- Inspect ground points and the main electrical grounds related to the PCM/TCM.
Step 3: Test the sensor and circuit (electrical test)
Refer to service data for the correct resistance values and pinout for the Subaru ISS in the CVT. If you don’t have exact specs, you can:
- Check for power/ground: With ignition on, verify there is reference voltage on the sensor circuit (often 5V on a control circuit) and a solid ground.
- Check signal path: With the engine running, observe the sensor signal (voltage or digital pulse) on the scan tool. The signal should respond smoothly to engine RPM and match the expected input shaft speed range.
- Look for shorts to ground or to VCC and for opens in the circuit. Any intermittent loss of signal is suspect.
If you have access to a multimeter and wiring diagram:
- Measure resistance between the sensor pins (as specified by Subaru service data) and compare to spec.
- Check continuity along the harness from the sensor to the TCM/ECU connector.
Step 4: Live data correlation (sensor vs vehicle speed)
- Monitor the input speed sensor reading vs engine RPM and vs vehicle speed when you perform a controlled drive:
- If input speed sensor RPM reading does not correlate with engine RPM or remains constant while the engine revs, suspect a bad sensor or a signaling issue.
- If vehicle speed and input speed readings are wildly out of sync or show erratic spikes, suspect wiring or sensor fault.
Step 5: Check for related codes and system health
- Scan for P0700 and related P07xx codes that indicate transmission controller faults.
- Check if Subaru-specific TCM software updates or service notes exist that address ISS circuit issues for your model year (no recalls were listed in the provided data, but TSBs could exist outside recalls; verify with dealer/service data).
Step 6: Fluid condition check (contextual)
- Check CVT fluid level and condition per Subaru service guidelines. Old, burnt, or contaminated fluid can contribute to transmission misbehavior and set fault conditions, though P0715 is sensor-focused. If fluid issues are evident, plan a CVT fluid service and re-test.
Step 7: Sensor replacement or wiring repair (if fault confirmed)
- If the ISS sensor or wiring is damaged or out of spec, replace the sensor and repair/recertify the wiring harness as needed.
- After repairs, clear the codes and perform a road test or drive cycle to verify the issue is resolved.
Step 8: If all electrical checks pass but fault persists
- Consider TCM/ECU software update or reflash if available from Subaru.
- If the fault remains and there are no other clear causes, the issue could be an intermittent sensor fault or an internal transmission control issue, which may require more in-depth testing or professional diagnosis.
Step 9: Post-repair verification
- After any repair, clear codes, perform a test drive across different speeds and loads, and re-scan to ensure P0715 does not return.
- Monitor live data during the test drive to confirm the ISS signal behaves correctly.
RELATED CODES
- P0710: Transmission Range Sensor Circuit Malfunction or related range signal issues.
- P0711: Input/Turbine Speed Sensor Circuit Range/Performance.
- P0712: Input/Turbine Speed Sensor Circuit No Signal or Malfunction (range/performance type, depending on manufacturer).
- P0713–P0714: Manufacturer-specific variations related to the same circuit family (notes: code numbers can vary by OEM; Subaru may implement close variants).
- P0700: Transmission Control System Malfunction (covers a broad range of transmission faults, often a umbrella code when multiple transmission codes are present).
REPAIR OPTIONS AND COSTS (2025 PRICES)
Note: These are approximate ranges common in the U.S. market. Actual prices depend on region, labor rate, and parts choice (OEM vs aftermarket).
Input Speed Sensor (ISS) replacement
- Parts: roughly $40–$120
- Labor: roughly $60–$180
- Total: roughly $100–$300
Wiring harness or connector repair
- Parts: $20–$100 (connector or harness sections)
- Labor: $60–$150 (depends on accessibility)
- Total: roughly $80–$250
Transmission fluid service (CVT fluid change or flush)
- Parts: $20–$60 (fluids and filters if applicable)
- Labor: $100–$250
- Total: roughly $120–$310
Transmission fluid filter or internal CVT maintenance (if recommended by Subaru service guidelines)
- Parts: $20–$100
- Labor: $100–$250
- Total: roughly $120–$350
Transmission Control Module (TCM) software update or reflash
- Parts: typically included; software update may be free at dealer or included in service
- Labor: $60–$200
- Total: roughly $60–$300 (varies; substantial repair if an actual TCM replacement is needed)
TCM replacement (if required)
- Parts: $200–$900 (depends on OEM vs aftermarket)
- Labor: $150–$600
- Total: roughly $350–$1500
Full transmission removal/replacement (rare for a sensor fault)
- Parts: varies
- Labor: $600–$1800+
- Total: can exceed several thousand dollars depending on extent
Important note: If the problem is strictly an electrical/connector issue, the most cost-effective route is sensor or wiring repair. If the issue is internal to the transmission or requires a TCM replacement, costs can be significantly higher.
DIY vs PROFESSIONAL
DIY-friendly aspects:
- Reading and interpreting OBD-II codes with a capable scanner.
- Visual inspection of sensor connectors and wiring harnesses.
- Basic electrical testing (voltage, continuity) if you have the right tools and know-how.
- Replacing the ISS sensor or repairing a damaged harness if you’re comfortable with transmission-area work and have access to service manuals.
Professional considerations:
- Transmission work, electrical harness diagnostics in hard-to-reach areas, and CVT-specific diagnostic procedures typically require specialized tools, wiring diagrams, and technician expertise.
- Subaru service information (procedure specifics, torques, pinouts) is important to avoid misdiagnosis.
- If software updates or TCM reprogramming is needed, a dealer or qualified shop is usually required.
Decision guide:
- If you can reliably test the sensor, wiring, and supply/ground and you find a clear fault in the sensor or harness, DIY is reasonable.
- If the fault persists after sensor/harness repair or you see multiple related codes, or you’re unsure about the electrical measurements, seek professional diagnosis.
PREVENTION
Regular CVT maintenance per Subaru guidelines:
- Use the specified Subaru CVT fluid. Do not mix fluids; use the correct fluid type and fill level.
- Schedule periodic CVT fluid changes at the intervals recommended in your owner’s manual (or sooner if you operate in severe conditions).
Inspect electrical connections:
- Periodically inspect the ISS wiring and connector for signs of wear, corrosion, or moisture.
- Ensure connectors are properly seated and guarded from moisture and debris.
Protect wiring harnesses:
- Keep harnesses routed away from heat sources and moving parts; use protective loom or conduit where rubbing is possible.
Gentle driving habits:
- Avoid aggressive starts or excessive wheel-spin that can stress the CVT and its sensors.
- Address transmission warnings promptly rather than continuing to drive.
Address issues early:
- If you notice intermittent transmission behavior or a CEL related to the transmission, diagnose early rather than waiting for a complete failure.
Data limitations recap
- The provided data shows no recalls for the model/year range in connection with P0715.
- There are no listed NHTSA owner complaints for this combination in the provided data.
- As a result, there are no model-specific frequency or fix statistics to rely on. Use general diagnostic steps and Subaru-specific service guidance for a robust approach.