P1758 on 2014-2015 Land Rover Range Rover Evoque: Transmission Fault Guide

What's Unique About the 2014-2015 Land Rover RANGE ROVER EVOQUE

The 2014-2015 Evoque and its platform-mate, the 2015 Discovery Sport, were among the first vehicles to use the then-new ZF 9HP48 9-speed automatic transmission. While ZF manufactures the transmission hardware, each automaker is responsible for developing the control software. Early production models from Land Rover, Jeep, and Honda using this transmission were susceptible to software-related issues as the technology was refined. Land Rover addressed these teething problems, including the fault that triggers P1758, through a series of software updates issued via Technical Service Bulletins (TSBs). Therefore, unlike many transmission codes that point to mechanical wear, P1758 on this specific vehicle is most often a pure software problem.

Diagnostic Flowchart

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

Symptoms You May Notice

• Transmission unexpectedly shifts into Neutral
• "Gearbox Fault" message on the instrument cluster
• Irregular, harsh, or jerky gear changes
• Inability to select forward or reverse gears
• Flashing gear selector indicator
• Check Engine Light or other transmission warning lights illuminated

Most Likely Causes

1. Outdated Transmission Control Module (TCM) Software 🔴 High Probability As documented in Land Rover TSBs LTB00736NAS1 (which supersedes Q500NAS1) and SSM72164, early versions of the software for the 9-speed transmission had errors that could lead to incorrect fault flagging. One specific issue mentioned in a recall document is an incorrect calculation of a solenoid learning function during an ECO Stop/Start event, leading to the fault. This was a widespread issue affecting the first wave of vehicles with the ZF 9HP48 gearbox.
   How to confirm: A Land Rover dealer or specialist with access to the TOPIx system can check the vehicle's VIN against service bulletins LTB00736NAS1 and recall P091 to see if the software update is applicable. Affected 2014-2015 Evoque VINs fall in the range EH795896 - FH996084 and FH000134 - FH077907.
   Typical fix: Update the TCM with the latest software version using Land Rover's diagnostic system (SDD or Pathfinder). This is often referred to as a transmission re-flash or calibration and is the specific action mandated by the TSBs.
   Est. part cost: $0

Rare But Worth Checking

• Insufficient Crimp in Transmission Wire Harness: A specific recall (P091 / NHTSA 16V-614) noted that insufficient crimps in the internal transmission harness could cause high electrical resistance, leading to the transmission shifting to neutral. The official remedy for this recall was not to replace the harness, but to apply a software update that would prevent the transmission from shifting into neutral even if this wiring fault occurred, effectively creating a software failsafe for a potential hardware issue.
• Failing Transmission Control Module (TCM): If a software update fails to resolve the issue or cannot be completed, the TCM itself may have a hardware fault. In this case, the module would require replacement and programming. A potential part number for the TCM in these vehicles is CEJ32-14C336-AA, though it should always be verified by VIN.

Diagnosis Steps

1. Confirm the presence of code P1758 (often with a -62 suffix) using an OBD-II scanner capable of reading transmission codes.
2. Contact a Land Rover dealer or qualified independent shop to check the vehicle's VIN for open recalls or applicable service bulletins. Specifically mention Recall P091 and TSB LTB00736NAS1 (which supersedes Q500).
3. If the TSB or recall is applicable, have the dealer perform the Transmission Control Module (TCM) software update using the SDD system. The technician will need to follow the on-screen prompts for 'Configure existing module - Transmission control module'.
4. During the update, the system may require the technician to visually locate and input the transmission serial number, which is found between the engine and air filter housing.
5. After the update, clear all DTCs and perform a thorough road test, including multiple stop/start cycles, to ensure the fault does not return.
6. If the code and symptoms persist after the software update, further diagnosis of the TCM hardware, wiring harness (checking for the crimp issue from recall P091), and internal transmission components may be necessary.

Parts You'll Likely Need

• Transmission Control Module (TCM) Software Update — This is not a physical part, but a service. It is the primary fix recommended by Land Rover to correct the logic error that causes code P1758.
  OEM price range: $200-$400
  Aftermarket price range: N/A
• Transmission Control Module (TCM) (OEM #CEJ32-14C336-AA) — In the rare event that the software update does not work or the module is unresponsive, the TCM itself may have failed and require replacement.
  Trusted brands: Land Rover (OEM)
  OEM price range: $400-$1200
  Aftermarket price range: N/A

Related Codes That Often Appear With This One

• P0795-04 — Listed in TSB SSM72164 as being caused by the same TCM software error.
• P07E3-07 — Listed in TSB SSM72164 as being caused by the same TCM software error.
• P0893-07 — Listed in TSB SSM72164 as being caused by the same TCM software error.
• P07E0-07 — Listed in TSB SSM72164 as being caused by the same TCM software error.

Technical Service Bulletins (TSBs) & Recalls

• LTB00736NAS1: This bulletin supersedes Q500NAS1 and Q450. It details the service action for both the Evoque and Discovery Sport for an irregular gear change or neutral selection, linking it to DTC P1758-62 and mandating a TCM software update.
• Q500NAS1: The original bulletin addressing an irregular gear change or neutral selection, linking it to DTC P1758-62 and mandating a TCM software update. Now superseded.
• SSM72164: Identifies P1758-62 and other codes as being caused by a 'TCM software error and/or engine torque issue', with the action being a software update.
• Recall P091 (NHTSA 16V-614): A safety recall for the Evoque and Discovery Sport due to 'insufficient crimps in a transmission wiring harness' that could cause a shift to neutral. The remedy was a TCM software update.

Platform-Specific Known Issues

• Land Rover issued a recall (P091) and multiple Technical Service Bulletins (Q500NAS1, SSM72164, LTB00736NAS1) for the 2014-2015 Evoque due to the 9-speed transmission unexpectedly shifting to neutral.
• The root cause was identified as a software error within the Transmission Control Module, which was corrected with a calibration update.
• The recall also acknowledged a potential wiring harness crimp issue that could cause the same symptom, but the prescribed fix was still the software update to act as a failsafe.

Mechanic-Grade Diagnostic Values

• Resistance of proportional clutch solenoids (Clutches B, C, D, E, TCC) — expected: 5.3 - 5.6 Ohms. Failure: A reading outside this range indicates a faulty solenoid.
• Resistance of proportional dog clutch solenoids (Dog Clutch A, F) — expected: 10.6 - 10.9 Ohms. Failure: A reading outside this range indicates a faulty solenoid.
• Resistance of electromagnetic park lock solenoid — expected: Approximately 24.6 - 25 Ohms. Failure: A reading significantly different from this value suggests a fault in the park lock mechanism's solenoid.
• Resistance of internal transmission wiring harness circuits — expected: Below 3.0 Ohms. Failure: Resistance above 3.0 Ohms indicates an open or high-resistance fault in the harness, which aligns with the known 'insufficient crimp' issue.

Hidden / Shadow Codes Worth Checking

• P1758-62: Defined as 'Signal Compare Failure' or 'Incorrect Current'. A Japanese recall notice provides a specific root cause: during an ECO Stop/Start event, the TCM software can incorrectly sample a low current value from a clutch solenoid. This bad value is then used as a learned threshold, causing the system to later misdiagnose a valid current as a fault, triggering the code and shifting to neutral. (see via A professional scan tool capable of reading manufacturer-specific codes from the Transmission Control Module (TCM), such as the Land Rover SDD system.)

Scan Tool Commands That Help

• Land Rover SDD (Symptom Driven Diagnostics): Configure existing module - Transmission control module — This is the primary service function mandated by TSBs LTB00736NAS1 and P091 to load the updated software calibration that corrects the P1758-62 fault.
• Land Rover SDD (Symptom Driven Diagnostics): Touchpoint Adaption reset procedure — This procedure resets the transmission's learned shift adaptations. It should be performed after a software update or if shift quality issues are present. It requires specific conditions: ATF temperature > 30°C (86°F), engine at idle, and brake applied.

Wiring & Ground Locations

• Transmission Serial Number — On the transmission casing, visible when looking down between the engine and the air filter housing. A flashlight is required to see it.. During the 'Configure existing module' software update procedure using SDD, the technician may be prompted to manually enter this serial number to ensure the correct calibration file is applied.
• Internal Transmission Wiring Harness — Located inside the transmission, connecting the TCM/valve body to the various solenoids and sensors.. Recall P091 identified that 'insufficient crimps' in this specific harness could cause high resistance, leading to the symptoms of P1758. While the software update was the official fix, a persistent fault after the update could point to a severe case of this harness issue requiring physical inspection or replacement.

Real Owner Repair Stories

• Reddit user in r/LandRover (2015 Range Rover Evoque, 55k miles) — Vehicle unexpectedly shifted into neutral while driving, displaying a 'Gearbox Fault' message. A fault code related to the issue was stored.
  ❌ Tried (didn't work) The owner was quoted $15,000 by the dealer for a full transmission replacement.
  ✅ What actually fixed it The owner was aware of the safety recall (P091) for this exact issue, which specifies a software update as the remedy, not a transmission replacement. The discussion strongly implies the correct fix is the software update, highlighting a common and costly misdiagnosis by service centers unfamiliar with the specific TSB.

OEM Part Supersession History

• CEJ32-14C336-AA → No direct supersession found. — This is the primary part number for the TCM used in this vehicle range.
  Heads up: When replacing the TCM, the new module must be programmed to the vehicle's VIN using Land Rover's SDD software. An alternative to a new OEM part is a remanufacturing service, where data from the original failed module is cloned to a repaired unit, making the replacement 'plug-and-play' without the need for dealer programming.

Model Year Variations Within This Range

• 2014-2015: The 2014 model year was the first to feature the ZF 9HP48 9-speed automatic transmission, replacing the previous 6-speed. This new transmission and its initial control software are the source of the P1758 issue. Earlier (pre-2014) Evoque models with the 6-speed transmission are not affected by this specific software-driven fault.