P0600 on 2014-2015 Land Rover Range Rover Evoque: Causes and Fixes for Serial Link Failure

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

Unlike the generic definition which could point to any number of modules, on the 2014-2015 Evoque this code is strongly associated with a specific, documented manufacturing defect. Land Rover issued Technical Service Bulletin (TSB) #LTB00740NAS2 identifying a faulty crimp on the internal transmission wiring harness as the primary cause for P0600, often accompanied by a 'Gearbox Fault' message. The TSB specifies that this issue applies to vehicles with a transmission serial number of 141772 or lower. This makes diagnosis more direct than on other vehicles where P0600 can be a much broader and harder-to-trace issue.

Diagnostic Flowchart

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

Symptoms You May Notice

• 'Gearbox Fault' message on the instrument cluster.
• Check Engine Light is on.
• Transmission gets stuck in one gear (limp mode).
• Harsh or erratic shifting.
• Vehicle may not start or may stall.
• ABS and Traction Control lights may illuminate.
• Flashing gear selector indicator ('R' for example) on the dash.
• Inability to select Drive or Reverse from Park.

Most Likely Causes

1. Faulty Crimp on Internal Transmission Wiring Harness 🔴 High Probability This is a known manufacturing defect documented by Land Rover in Technical Service Bulletin LTB00740NAS2 for the 2014-2015 Evoque with the ZF 9HP48 transmission. It specifically affects transmissions with serial number 141772 or lower.
   How to confirm: A technician must verify the presence of P0600-04 and other related codes listed in the TSB. The transmission serial number must be checked to confirm it falls within the affected range. If so, diagnosis proceeds directly to replacing the harness.
   Typical fix: Replace the transmission solenoid valve electrical harness (also called the sensor unit) inside the transmission oil pan. This requires draining the fluid and removing the valve body to access the harness.
   Est. part cost: $150-$250
2. Low Battery Voltage or Faulty Auxiliary Battery 🟡 Medium Probability Land Rovers are notoriously sensitive to voltage. A weak main battery or a failing auxiliary battery (located under the glove box on these models) can cause a cascade of communication errors, including the 'Gearbox Fault' message. The auxiliary battery powers the gearshift module during start/stop events.
   How to confirm: Test the main battery voltage with the engine off (~12.6V) and while running (~13.5-14.5V). Check for corrosion. Many owners on forums report that replacing the small auxiliary battery (Part No. LR024953 or a PowerSonic PS-1212 equivalent) resolved their 'Gearbox Fault' warnings.
   Typical fix: Charge or replace the main battery. Replace the auxiliary battery module located behind/under the glove compartment.
   Est. part cost: $20-$40 for auxiliary battery, $200-$450 for main battery.
3. Failed Transmission Control Module (TCM) ⚪ Low Probability While less common than the wiring issue, the module itself can fail electronically. This is often a diagnosis of exclusion.
   How to confirm: This is a diagnosis of exclusion. If the wiring harness (per the TSB), power/ground supplies, and CAN network integrity are all confirmed to be good, but communication is still absent, the module itself is suspect.
   Typical fix: Replace the Transmission Control Module and program it to the vehicle using JLR-specific diagnostic tools.
   Est. part cost: $800-$1500

Rare But Worth Checking

• Failed Powertrain Control Module (PCM): This is very rare. The PCM is the central computer, and its failure can cause a P0600 code, but it's much less likely than the specific wiring, battery, or TCM issues on this vehicle. Replacement is expensive, often exceeding $2,000.
• Damaged CAN Bus Wiring: Physical damage to the main communication network wires from an accident, rodent damage, or corrosion at a connector can cause this code, but it's less common than the specific TSB-related harness failure.
• Water Intrusion into an ECU: In a forum post for a different Land Rover model, a user reported that a P0600 code was resolved after cleaning and drying the transmission ECU which had suffered from water damage. While not specific to the Evoque, it's a plausible, though rare, cause.

Diagnosis Steps

1. Scan all vehicle modules for stored Diagnostic Trouble Codes (DTCs). Note if P0600-04 and other codes mentioned in TSB LTB00740NAS2 are present.
2. Check the main battery and charging system. Ensure voltage is stable and above 12.4V with the engine off. A running voltage should be around 13.5-14.5V. Clean any corrosion from terminals.
3. Check the auxiliary battery located behind the glove box. Many owners report low voltage on this battery causes gearbox faults. Consider replacing it as a low-cost diagnostic step.
4. If codes from TSB LTB00740NAS2 are present, follow the TSB instructions. This involves inspecting the transmission serial number to confirm applicability (must be 141772 or lower).
5. If the TSB applies, the next step is to gain access to the transmission's internal components to replace the solenoid valve electrical harness. This involves draining fluid and removing the valve body.
6. If the TSB does not apply, perform a full diagnostic of the CAN network. Check for power and ground at the TCM connector.
7. Use a multimeter or oscilloscope to check for signal integrity on the CAN wires at the TCM. Look for 60 ohms of resistance across the CAN high and low wires with the battery disconnected.
8. If wiring is confirmed good, the TCM may be faulty. If the TCM is replaced, it will require programming to the vehicle using a JLR-approved diagnostic tool.

Parts You'll Likely Need

• Transmission Solenoid Valve Electrical Harness (OEM #LR049888) — This is the part identified in Land Rover TSB LTB00740NAS2 as the cause of the faulty crimp leading to code P0600. This part has been superseded by LR086170.
  Trusted brands: Land Rover (OEM)
  OEM price range: $150-$250
  Aftermarket price range: $100-$180
• Auxiliary Battery (OEM #LR024953) — A failing auxiliary battery is a very common cause of 'Gearbox Fault' messages on the Evoque and is a recommended first check due to its low cost and ease of replacement. An aftermarket equivalent is the PowerSonic PS-1212.
  Trusted brands: Land Rover (OEM), PowerSonic
  OEM price range: $50-$80
  Aftermarket price range: $20-$40
• Transmission Service Kit (OEM #LR049876) — If replacing the internal harness, you will also need a new transmission pan gasket, filter, and the correct fluid, which often come in a service kit as specified by the TSB.
  Trusted brands: Land Rover (OEM), ZF
  OEM price range: $100-$200
  Aftermarket price range: $70-$150

Related Codes That Often Appear With This One

• P0710 — Transmission Fluid Temperature Sensor Circuit Malfunction. This code is explicitly listed in TSB LTB00740NAS2 as appearing with P0600 due to the faulty internal harness.
• P0712 / P0713 — Transmission Fluid Temperature Sensor Circuit Low/High. Also listed in the TSB as related to the same wiring harness fault.
• P0975 / P0978 / P0981 / P0984 — Shift Solenoid circuit codes. These are also mentioned in TSB LTB00740NAS2 and are direct consequences of the faulty internal transmission wiring harness.
• P099B-14 — Shift Solenoid 'G' Control Circuit Low. This is another code specifically mentioned in a version of the TSB related to the harness failure.

Technical Service Bulletins (TSBs) & Recalls

• LTB00740NAS2: Addresses a 'Gearbox fault' message with DTC P0600-04 and other related codes, identifying a faulty crimp on the internal transmission wiring harness as the cause.

Platform-Specific Known Issues

• A 'Gearbox fault' message accompanied by P0600-04 and other transmission codes is the subject of Land Rover Technical Service Bulletin LTB00740NAS2, which points to a faulty crimp on the internal transmission wiring harness for transmissions with serial number 141772 or lower.
• Many owners in forums like babyRR.com and Reddit report that 'Gearbox Fault' messages, sometimes without a P0600 code, were resolved by simply replacing the small auxiliary battery located under the glove compartment.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: ~60 Ohms. Failure: A reading of 120 Ohms indicates an open circuit or a missing termination resistor. A reading well below 60 Ohms could indicate a shorted module or extra resistor on the network.
• CAN Bus Voltage (Ignition ON) — expected: CAN High (CAN-H) line should be ~2.65V; CAN Low (CAN-L) line should be ~2.35V.. Failure: Significant deviation from these voltages suggests an open or short circuit on the network.
• Auxiliary Battery Voltage (Key-On, Engine-Off) — expected: 12.5V or higher.. Failure: A reading below 12.0V, especially in the 8V-11V range, indicates a failing battery that can cause various electronic faults.
• TCM Power and Ground at Connector — expected: Consistent 12V supply at the power pin and less than 0.1 Ohm resistance to chassis on the ground pin.. Failure: Fluctuating voltage or high resistance on the ground pin indicates a wiring issue, not a faulty TCM.
• ZF 9HP48 Dog Clutch F Solenoid Resistance — expected: Between 10.0 and 12.0 Ohms.. Failure: A reading outside this range indicates a faulty solenoid, which is part of the internal harness assembly.

Hidden / Shadow Codes Worth Checking

• P0600-04: The '-04' suffix indicates a 'System Internal Failure'. This is the specific variant of P0600 cited in TSB LTB00740NAS2, pointing directly towards an internal transmission hardware issue (the wiring harness) rather than a generic communication loss. (see via A professional Land Rover-compatible diagnostic tool like JLR SDD, Pathfinder, or high-end Autel/Launch scanners.)

Scan Tool Commands That Help

• JLR SDD / Pathfinder: Configure new module - Transmission Control Module — This function is required after replacing the Transmission Control Module (TCM) to program it to the vehicle and synchronize the VIN.
• JLR SDD / Pathfinder / iCarsoft LR Series: Reset Adaptation / Clear adaptation values — After replacing the internal transmission harness or the TCM, the learned shift adaptations must be cleared. A re-learn drive cycle must be performed afterward for the transmission to shift smoothly.

Wiring & Ground Locations

• Transmission Control Module (TCM) — On 2012–2018 Evoques, it's typically mounted vertically behind the passenger-side front wheel well liner.. This is the module that loses communication, triggering P0600. Checking its connector for corrosion and verifying power/ground at this location is a key diagnostic step.
• TCM Ground Points — There are two primary grounds for the TCM: one at the transmission casing itself and another at a chassis ground point near the battery.. A poor ground connection is a common cause of communication faults and can mimic the failure of a module. Resistance between the TCM connector ground pin and the chassis should be less than 0.1 ohm.
• Diagnostic Link Connector (DLC) / OBD-II Port — Under the driver's side dashboard.. The CAN bus resistance (should be 60 Ohms) can be measured between Pin 6 (CAN-H) and Pin 14 (CAN-L) at the DLC with the battery disconnected to quickly assess the health of the entire network backbone.

Real Owner Repair Stories

• babyRR.com user 'HtownBlue' (2013 Evoque 2.2 SD4) — Intermittent 'Gearbox Fault' message, engine light stays on, gear selector gets stuck in Park.
  ❌ Tried (didn't work) Main battery tested OK., Stop/start battery under the hood was replaced but the fault returned.
  ✅ What actually fixed it Replacing the small auxiliary battery located under the glove compartment solved the gearbox code and fault messages.
• YouTube video by 'BigDudeTV' (Range Rover Evoque) — 'Gear Box Fault' message on the dashboard.
  ❌ Tried (didn't work) Initial diagnosis pointed towards a major transmission issue.
  ✅ What actually fixed it The problem was resolved by replacing the small auxiliary battery (PS1212 equivalent) located behind the passenger side glove box. The video provides a step-by-step guide on how to access and replace it without special tools.

OEM Part Supersession History

• LR049888 → LR086170 — The original harness (LR049888) is the part identified in TSB LTB00740NAS2 as having a faulty crimp. The superseding part, LR086170, is the revised component designed to correct this manufacturing defect.