Diagnostic Trouble Codes (DTCs) are the first clue in any Jaguar Land Rover repair. But a code alone does not tell the whole story. Understanding the probable cause, the recommended diagnostic path, and the right tool for the job saves hours of guesswork. This reference covers the most common DTCs across all major JLR systems.
Engine DTCs
| Code | Description | Probable Cause | Fix | Tool |
|---|
| P0016 | Crankshaft / Camshaft Position Correlation | Stretched timing chain, worn tensioner, failed VVT solenoid | Measure chain stretch, replace tensioner and solenoid if out of spec | Pathfinder / SDD |
| P0087 | Fuel Rail Pressure Too Low | High-pressure fuel pump failure, clogged filter, leaking injector | Test fuel pressure at rail, replace pump or filter | Pathfinder / SDD |
| P0299 | Turbocharger Underboost | Stuck wastegate, boost leak, failed turbo actuator | Smoke test intake, inspect actuator and vacuum lines | Pathfinder / SDD |
| P0420 | Catalyst System Efficiency Below Threshold | Worn catalytic converter, O2 sensor degradation, exhaust leak | Check exhaust for leaks, test converter efficiency, replace if failed | Pathfinder / SDD |
| P0300 | Random / Multiple Cylinder Misfire | Spark plugs, ignition coils, fuel injector, low compression | Read live misfire data, swap coils to isolate, perform compression test | Pathfinder / SDD |
Transmission DTCs
| Code | Description | Probable Cause | Fix | Tool |
|---|
| P0705 | Transmission Range Sensor Circuit | Faulty TRS, wiring corrosion, misadjusted selector cable | Test TRS resistance, adjust cable, replace sensor if failed | Pathfinder / SDD |
| P0730 | Incorrect Gear Ratio | Worn clutch packs, low fluid, failed solenoid | Check fluid level and condition, perform adaptation, replace solenoid body | Pathfinder / SDD |
| P0776 | Pressure Control Solenoid B | Solenoid body internal fault, contaminated fluid | Replace solenoid body, flush transmission, refill with correct fluid | Pathfinder / SDD |
| P1722 | Transmission Speed Sensor Error | Faulty output speed sensor, damaged tone ring | Replace speed sensor, inspect tone ring on output shaft | Pathfinder / SDD |
| U0101 | Lost Communication with TCM | CAN bus fault, TCM power issue, corrupted TCM software | Check TCM power and ground, verify CAN bus resistance, reflash TCM | JET-PRO / Pathfinder |
ABS / Chassis DTCs
| Code | Description | Probable Cause | Fix | Tool |
|---|
| C0035 | Left Front Wheel Speed Sensor Circuit | Broken sensor, damaged wiring, debris on tone ring | Inspect sensor and wiring, clean tone ring, replace sensor | Pathfinder / SDD |
| C0051 | Steering Wheel Position Sensor | Failed SAS, misaligned steering column, clock spring fault | Recalibrate SAS, replace clock spring if steering controls also faulty | Pathfinder / SDD |
| C1A00 | ABS Module Internal Fault | Internal valve failure, corrupted calibration | Attempt recalibration, replace ABS module if internal fault persists | Pathfinder / SDD |
| U0121 | Lost Communication with ABS | CAN bus open circuit, ABS module power loss | Check ABS module fuses, measure CAN bus continuity, verify module power | SX-CAN / Pathfinder |
Airbag / Restraint DTCs
| Code | Description | Probable Cause | Fix | Tool |
|---|
| B0001 | Driver Frontal Deployment Loop | Bad clock spring, open circuit in steering wheel harness | Replace clock spring, inspect steering wheel harness | Pathfinder / SDD |
| B0020 | Side Airbag Deployment Loop | Seat connector corrosion, damaged seat harness | Inspect seat connectors, repair or replace harness | Pathfinder / SDD |
| B100D | ECU Configuration Mismatch | Wrong CCF, replaced module not configured | Read CCF, verify airbag module part number, reconfigure with correct CCF | CCF-PRO / Pathfinder |
| U2018 | Restraint System Communication Fault | CAN bus issue, module power loss, internal module fault | Check restraint module fuses, verify CAN bus, test module | Pathfinder / SDD |
HVAC DTCs
| Code | Description | Probable Cause | Fix | Tool |
|---|
| B1038 | Evaporator Temperature Sensor | Failed sensor, open circuit, connector corrosion | Test sensor resistance, check wiring, replace sensor | Pathfinder / SDD |
| B1089 | Blower Motor Control Circuit | Failed blower motor, bad resistor, FET failure | Test blower motor current, replace resistor or control module | Pathfinder / SDD |
| B10A2 | Refrigerant Pressure Sensor | Sensor failure, low refrigerant, overpressure | Recover refrigerant, test pressure transducer, recharge to spec | Pathfinder / SDD |
| U0155 | Lost Communication with IPC | CAN bus fault, IPC power loss, corrupted IPC software | Check IPC power, verify CAN bus, reflash IPC if needed | Pathfinder / JET-PRO |
Infotainment DTCs
| Code | Description | Probable Cause | Fix | Tool |
|---|
| U3000 | Control Module Internal Fault | Corrupted IMC software, failed eMMC/NAND | Reflash IMC or perform virginize and repair | SX-tool / Pathfinder |
| U3000-49 | Control Module Internal Fault — Software | Bootloader corruption, incomplete update | Forced programming or IMC virginize | SX-tool / JET-PRO |
| U3000-87 | Control Module Internal Fault — Bus | Lost communication with network, CAN bus error | Check MOST/CAN bus, verify IMC power, reflash | SX-CAN / Pathfinder |
| B100D-31 | Configuration Mismatch — IMC | CCF does not match IMC hardware level | Update CCF to match IMC part number, reflash IMC | CCF-PRO / Pathfinder |
| U0232 | Lost Communication with Touch Screen | Loose LVDS cable, failed TSU, software fault | Reseat LVDS cable, reflash TSU, replace if hardware failed | Pathfinder / SDD |
When to Use Which Tool
Not every DTC requires the same diagnostic approach. Use this guide to select the right tool for the job:
- Pathfinder / SDD: For standard DTC reading, guided diagnostics, and module calibration on supported vehicles. Pathfinder for MY2017+, SDD for pre-2017.
- SX-tool: For IMC virginize, SPC5 programming, CCF editing, and advanced module recovery where dealer tools fail or are unavailable.
- JET-PRO: For ECU flash programming, forced programming mode, and security seed-key calculations on modules that require offline unlocking.
- SX-CAN: For CAN bus analysis, physical layer diagnostics, and data logging when you suspect wiring or termination issues.
Always start with the simplest explanation. A U-code (communication fault) is more likely caused by a corroded connector or blown fuse than by a failed module. Check power, ground, and bus continuity before replacing any ECU.
Conclusion
This reference covers the most frequently encountered DTCs in JLR workshops, but it is not exhaustive. Every DTC should be interpreted in context: consider the vehicle's service history, recent repairs, and any aftermarket modifications. With the right diagnostic tool and a methodical approach, even the most complex JLR fault can be traced to its root cause and fixed efficiently.
