P1731

Code

LAND ROVER P — Powertrain

Inconsistent gear relationship

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 19 EN: 22 RU: 29

AI status

Completed

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Page language: EN

Causes

Faulty or misadjusted transmission range (gear position) sensor/switch
Failed or intermittent transmission speed sensors (input/turbine or output shaft)
Faulty shift solenoid(s) or hydraulic control (sticking, electrical fault)
Low or contaminated transmission fluid, incorrect fluid level
Wiring or connector faults between TCM and transmission sensors/solenoids
Mechanical transmission faults (worn clutch packs, damaged planetary gear set)

Symptoms

Illuminated MIL / transmission warning light
Incorrect gear indicated or gear indicator flashing
Harsh, delayed, or abnormal shifting
Vehicle may limp-home or be stuck in one gear
Unusual noises from transmission (grinding, whining) under load
Erratic speedometer reading if output speed sensor affected

What to check

Read and record all stored and pending codes, freeze frame and live PIDs
Check battery voltage and charging system (low voltage can cause faults)
Inspect transmission fluid level, color and odor; correct if necessary
Visually inspect wiring and connectors to TCM, range sensor, speed sensors and solenoids for corrosion, damage or poor connections
Monitor input (turbine) and output speed sensor signals during drive or on a scope
Confirm gear position reported by PRNDL/range sensor matches selector lever

Signal parameters

Input (Turbine) speed (rpm) — should rise with engine rpm when in gear
Output (Transmission/Vehicle) speed (rpm or km/h) — should increase with vehicle speed
Calculated gear ratio = input speed / output speed — expected ranges by gear; mismatch triggers P1731
TCM gear requested vs actual gear PID — should match when transmission is healthy
Shift solenoid command (ON/OFF or PWM duty) vs solenoid current/voltage — should respond to TCM commands
Transmission fluid pressure (line/accumulator) — should be within spec under commanded conditions

Diagnostic algorithm

Retrieve and document all DTCs, freeze frame data and live PIDs. Note multiple transmission codes that may point to a common issue.
Check battery voltage and charging (>=12.4 V at rest, >=13.5 V running). Low voltage can cause communication and solenoid faults.
Inspect transmission fluid level and condition. Top up or change fluid if low/contaminated, then clear codes and re-test.
Visually inspect connectors and wiring for corrosion, bent pins, chaffing, or water ingress at the range sensor, speed sensors and TCM. Repair as needed.
Monitor input and output speed sensors while driving or on a lift: verify both sensors produce clean, proportional signals and that calculated gear ratio matches expected values for each gear.
Verify the transmission range (gear position) sensor/switch reports the selector position accurately. If mismatch, adjust/replace sensor.
Command shift solenoids via scan tool (if supported) and observe voltage/current and transmission response. Replace any solenoid failing to switch or out of spec.
If electrical checks pass but ratio mismatch remains, perform hydraulic tests (line pressure checks) and consider internal mechanical inspection (clutch packs, bands, planetary gears).
Check for and apply any TCM software updates or calibrations. Reprogram/replace TCM only after verifying external causes are addressed.
After repairs, clear codes and perform a complete drive cycle while logging relevant PIDs to confirm the fault does not return.

Likely causes

Intermittent or incorrect speed sensor signal (input vs output mismatch)
Transmission range sensor misreporting gear selection
One or more shift solenoids not switching correctly or electrical open/short
Low fluid level or degraded fluid causing delayed/clumsy shifts
Wiring/connectors at transmission harness corroded or damaged

Fault status

⚠️ Status

Transmission control module has detected an inconsistent gear relationship — actual transmission ratio or gear state differs from the commanded/expected state.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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P1731 — Inconsistent gear relationship