P0715 on 2017-2018 Land Rover Discovery: Input Speed Sensor Fault Causes & Fixes

What's Unique About the 2017-2018 Land Rover DISCOVERY

What makes this code unique on the 2017-2018 Discovery is that it's rarely due to a failed sensor. Instead, it's a well-documented software flaw triggered by the vehicle's Eco Stop/Start system. TSB SSM73847 notes this issue typically occurs on low-mileage vehicles, often under 2,500 miles (4,000 km). During an auto-restart, the TCM can become confused and misinterpret the input speed sensor's signal, logging the fault. This specific scenario is the subject of multiple manufacturer technical service bulletins, making a software update the primary and most critical diagnostic step.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• A 'Gearbox Fault' warning message displayed on the instrument cluster.
• The 'D' for Drive flashes on the gear selector switch and/or the instrument cluster.
• The issue frequently occurs immediately following an Auto Stop/Start event.
• Erratic or harsh shifting.
• Transmission may be stuck in a single gear (limp mode).
• Delayed gear engagement when shifting from Park.

Most Likely Causes

1. Outdated Transmission Control Module (TCM) Software 🔴 High Probability → Shop Transmission Assembly A documented software logic flaw related to the Eco Stop/Start system causes the TCM to misinterpret the sensor signal during an engine restart, as per TSBs LTB01205NAS1 and SSM73847.
   How to confirm: A Land Rover dealer or specialist with the appropriate diagnostic tool (Pathfinder loaded with version 170 or later) can check the current software version against the latest available one. The TSBs are the primary confirmation.
   Typical fix: Updating the TCM to the latest software version. TSB SSM73847 also specifies performing an 'adaption drive cycle' using Pathfinder until a minimum of 3 counts are achieved for each clutch.
   Est. part cost: $0
2. Faulty Input/Turbine Speed Sensor ⚪ Low Probability → Shop Automatic Transmission Input Shaft Speed Sensor While less common on this platform due to the known software issue, the sensor can still fail. However, on the ZF 8HP transmission, the input speed sensor is a Hall Effect sensor (designated G182) integrated into the mechatronic unit (valve body) and is not typically serviced as a separate component.
   How to confirm: If the code returns after a software update and adaption learn, a technician will monitor the sensor's live data for dropouts. Testing the sensor's resistance would require accessing its terminals at the mechatronic unit inside the transmission. A healthy sensor should have a resistance between 1,000-2,000 ohms. Testing or replacement requires removing the transmission pan and the entire mechatronic/valve body assembly.
   Typical fix: Replacing the entire mechatronic (valve body) assembly. This is a labor-intensive and expensive repair.
   Est. part cost: $350-$400
3. Wiring Harness or Connector Issue ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness between the transmission's main connector and the TCM for damage, especially near hot or moving parts. Check the main transmission connector for corrosion, moisture, or loose pins.
   Typical fix: Repairing the damaged wire or cleaning/securing the connector.
   Est. part cost: $5-$50

Rare But Worth Checking

• Failing Transmission Control Module (TCM): → Shop Transmission Assembly This is a last resort. A hardware failure in the TCM is rare and should only be considered after software, sensor, and wiring have been definitively ruled out. The TCM is integrated with the mechatronic unit inside the transmission.
• Faulty Mechatronic Valve Body Assembly: → Shop Transmission Valve Body TSB SSM73847 mentions this as a possibility if a software update and adaption learn do not resolve the issue. In this case, the dealer is instructed to capture adaption data and submit it to a ZF Transmission Engineer for review before replacing parts.

Diagnosis Steps

1. Scan the Transmission Control Module (TCM) for codes. Confirm the presence of P0715-64 and P0700-02. If other codes are present, they must be diagnosed first.
2. Check for applicable Technical Service Bulletins. TSBs LTB01205NAS1 and SSM73847 directly address this specific fault scenario.
3. Connect a JLR-approved Midtronics battery power supply to the vehicle to maintain stable voltage during programming.
4. Using a Land Rover-approved diagnostic tool (Pathfinder v170 or later), verify the current TCM software version. If an update is available, perform the 'Configure existing module - Transmission control module' software update as the primary fix.
5. Clear the DTCs. Perform an adaption drive cycle using the Pathfinder utility 'Transmission control module adaption learn' until a minimum of 3 counts are achieved for each clutch.
6. Perform a road test, including several Auto Stop/Start cycles, to confirm the fault does not return.
7. If the code returns after the software update, the issue may be with the mechatronic unit. The dealer would then capture adaption data and submit a technical assistance request for review by a ZF engineer before proceeding with parts replacement.
8. If directed to investigate the sensor circuit, inspect the wiring harness and main transmission connector for damage, corrosion, or loose pins.

Parts You'll Likely Need

• Transmission Mechatronic Unit / Valve Body — This is the part to replace ONLY if the well-documented software update does not fix the issue and the fault is traced to the internal mechatronics. The input speed sensor is integrated into this assembly and is not sold separately for the ZF 8HP transmission.
  Trusted brands: Genuine Land Rover, ZF
  OEM price range: $1100+
  Aftermarket price range: $800-$1200

Related Codes That Often Appear With This One

• P0700 — P0700 is a generic code that acts as a 'check engine light' for the transmission. It simply means the Transmission Control Module (TCM) has stored a fault, which in this case is the more specific P0715 code. 🎬 See this video for a breakdown of the P0715 fault code. The TSBs confirm P0700-02 is expected to appear with P0715-64.

Technical Service Bulletins (TSBs) & Recalls

• LTB01205NAS1: Addresses a flashing 'D' on the gear selector and codes P0715-64/P0700-02 after an Auto Stop/Start event. Identifies the cause as a TCM software error and provides instructions for an update using Pathfinder v170 or later. Affects 2018 Discovery, Velar, Range Rover, and Range Rover Sport.
• SSM73847: Also identifies P0715-64 and a flashing 'D' following an ECO Stop/Start event, noting it's common on low-mileage (under 2,500 miles) vehicles. Points to either a TCM software error fixed by an adaption learn cycle, or more rarely, a fault in the mechatronic valve block requiring engineer review.

Platform-Specific Known Issues

• The 2017-2018 Discovery (VIN range 047448-073283 for 2018 models) is highly prone to this code being triggered by a TCM software error related to the auto stop/start system. Land Rover has issued specific bulletins (LTB01205NAS1, SSM73847) to address this, making a software check the mandatory first step.
• TSB SSM73847 notes this issue typically occurs on low-mileage vehicles (under 2,500 miles) equipped with the 8HP45 or 8HP70 automatic transmission.

Mechanic-Grade Diagnostic Values

• Input Speed Sensor Resistance — expected: 1,000 - 2,000 Ohms. Failure: A reading significantly outside this range, or an open loop (OL) reading, suggests a failed sensor.
• Input Speed Sensor Signal Voltage — expected: A pulsing digital signal (square wave) or AC voltage that increases in frequency and/or amplitude with RPM. Generally between 0.5V and 12V.. Failure: A flat 0V, a constant high voltage, or an erratic signal that doesn't correlate with engine RPM indicates a fault in the sensor or its circuit.

Scan Tool Commands That Help

• JLR Pathfinder (v170 or later): ECU Diagnostics -> Transmission Control Module (TCM) -> Configure existing module - Transmission control module — This is the specific service function used to perform the software update that is the primary fix for the P0715-64 fault, as per TSB LTB01205NAS1.
• JLR Pathfinder: ECU Diagnostics -> Transmission Control Module (TCM) -> Transmission control module adaption learn — This function must be run after clearing the DTCs (and after a software update, if performed). It requires a specific drive cycle until a minimum of 3 counts are achieved for each clutch to re-learn clutch engagement points.
• JLR Pathfinder: Capture a readout of the adaption data from the TCM — This is the required next step IF the software update and adaption learn drive cycle do NOT resolve the fault. The data file must be submitted via a Technical Assistance request to be reviewed by a ZF Transmission Engineer before any hardware (like the mechatronic unit) is replaced.

Wiring & Ground Locations

• TCM (Transmission Control Module) — Integrated into the mechatronic unit, which is located inside the transmission oil pan and bolted to the valve body.. Because the TCM is internal, all sensor wiring terminates inside the transmission. The only external test point is the main 16-pin round transmission case connector.
• Input Speed Sensor (G182) — This is a Hall Effect sensor mounted on the mechatronic unit inside the transmission. It reads a magnetic encoder wheel on the input shaft.. It is not an externally accessible or individually replaceable part. A failure of this sensor requires replacement of the entire mechatronic assembly.
• Main Transmission Harness Connector — A large, round 16-pin connector on the side of the transmission case.. This is the primary external point for any electrical testing of the transmission's internal components. Any wiring checks for opens, shorts, or continuity between the vehicle and the transmission would be performed here. Damaged pins or wires at this connector can cause the P0715 code.

Real Owner Repair Stories

• LandyZone - Land Rover Forum (2006 Land Rover Freelander (Note: Different model/transmission, but illustrates a relevant failure mode)) — Vehicle would not shift above 3rd gear and displayed an F4 error. After a reset, the fault would reappear around 25 mph.
  ❌ Tried (didn't work) A garage replaced the entire transmission with a secondhand unit, but the problem immediately returned.
  ✅ What actually fixed it The garage discovered that wires on the main 14-pin transmission connector had been damaged, likely during the transmission replacement. The final fix was to repair the damaged wiring at the connector. This story highlights how wiring issues can mimic major component failure and lead to expensive, unnecessary repairs.

Model Year Variations Within This Range

• 2018: TSB LTB01205NAS1 applies to 2018 Discovery models within the specific VIN range of 047448-073283, making it easy to confirm if a vehicle is covered by this specific software update bulletin.
• 2017-2018: TSB SSM73847 notes the issue is most prevalent on low-mileage vehicles, typically under 2,500 miles (4,000 km), equipped with either the 8HP45 or 8HP70 transmission.