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Home / DTC / P0493 — Fan speed excess (clutch locked)

P0493 — Fan speed excess (clutch locked)

Detailed page for trouble code P0493.

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Code

P0493

LAND ROVER P — Powertrain

Fan speed excess (clutch locked)

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Mechanical failure of fan clutch (viscous or electromagnetic) — stuck/locked
  • Shorted or welded relay in fan control circuit
  • Faulty fan control module or PCM output stage
  • Wiring fault (short to battery, short to ground, open, corrosion) between PCM and fan/clutch
  • Faulty fan speed sensor or inadequate RPM feedback
  • Faulty coolant temperature sensor or incorrect temperature input

Symptoms

  • Loud or continuous radiator fan noise (fan running constantly or at high speed)
  • Reduced fuel economy and increased engine load
  • Possible poor acceleration or rough idle under some conditions
  • Check Engine Light (MIL) illuminated
  • Unusual current draw from cooling fan circuit (high amperage)
  • Cooling fan appears to run even when not requested by HVAC or engine temp

What to check

  • Read freeze frame and live data with a capable scan tool: commanded fan duty, actual fan RPM (if available), engine coolant temperature, fan clutch status
  • Visually inspect fan assembly, clutch, wiring harness, connectors, and fuses for damage, corrosion, melted insulation, or signs of overheating
  • Check fan control relays and swap with a known good relay (if applicable) or bench test relay
  • Measure voltage at the fan/clutch control connector with engine off and while commanded on/off
  • Measure current draw of fan motor/clutch with an inductive amp clamp during operation
  • Listen/observe at ignition off / key on to determine if clutch is mechanically locked

Signal parameters

  • Fan command: PWM duty cycle or ON/OFF request from PCM (0–100% or discrete on/off)
  • Fan actual speed: fan RPM or inferred speed higher than expected for given engine coolant temperature and commanded duty
  • Control voltage to clutch: typically 0–12 V (vehicle-specific)
  • Current draw: significantly above normal idle values (varies by vehicle and fan; abnormal high amps indicate mechanical lock)
  • Engine coolant temperature: compared against fan run thresholds (e.g., fan commanded at normal temp range)
  • Relay coil voltage and continuity: battery voltage when energized, continuity when de-energized

Diagnostic algorithm

  1. Capture freeze frame and live data: note coolant temp, fan command, fan RPM/feedback, and any related PID values.
  2. With engine cold, key on engine off: inspect connector and wiring to fan/clutch for battery voltage or ground presence indicating a stuck relay or short.
  3. Start engine and observe fan behavior while monitoring commanded fan duty and fan RPM. Compare fan RPM to expected values for that temperature and command.
  4. Check fuses and relays in fan circuit; swap relay with matching relay if available to check for relay failure.
  5. Measure current draw of the fan/clutch with amp clamp while fan is operating. Excessive current suggests mechanical seizure or locked clutch.
  6. If available, command fan on/off with scan tool and observe whether PCM command correlates with fan behavior. If fan runs regardless of command, suspect mechanical lock, stuck relay, or short to battery.
  7. Inspect and test fan speed sensor (if used) and its wiring for open/short; verify correct RPM feedback to PCM.
  8. If electrical control and sensors check out, remove and bench-test the fan clutch or fan motor assembly to verify mechanical freedom and correct operation. Replace assembly if seized or internally shorted.
  9. If fan assembly tests good, verify PCM/fan control module outputs with an oscilloscope or DVOM while commanding fan; repair or replace control module/PCM as last resort and only after verifying wiring and loads are correct.
  10. Clear codes and road-test to confirm repair; monitor live data to ensure fan behavior and temperatures are within normal ranges.

Likely causes

  • Fan clutch mechanically seized/locked
  • Control relay welded closed or relay stuck
  • Shorted power feed to fan/clutch causing continuous engagement
  • Faulty fan speed feedback (sensor or connector) producing false high reading
  • PCM or fan control module driver failure

Fault status

⚠️ Status
Cooling fan running at excessive speed or clutch appears locked; PCM detected abnormal fan control/performance.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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413

Browse 413 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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