Code
P101E
RENAULT
P — Powertrain
- Engine coolant 'hot' warning lamp - circuit malfunction
Views:
UK: 10
EN: 13
RU: 8
AI status
Completed
Completed
100%
Causes
- Damaged, corroded or disconnected wiring / connector in coolant temperature lamp or sensor circuit
- Faulty engine coolant temperature (ECT) sensor (NTC) or its harness
- Faulty instrument cluster or warning lamp bulb/LED driver
- Blown fuse or faulty relay supplying the lamp or cooling system control
- Cooling system fault causing genuine overheating (low coolant, stuck thermostat, failed water pump)
- Cooling fan control fault (fan relay, fan motor, fan control module)
Symptoms
- Coolant ‘hot’ warning lamp illuminated or flashing on the dash
- Intermittent or permanent loss of coolant temperature gauge or wrong temperature reading
- Cooling fan(s) not engaging when temperature rises
- Visible coolant loss, steam, or engine overheating symptoms (reduced power, limp mode)
- Possible stored or active diagnostic trouble codes related to coolant temperature or fan control
What to check
- Read fault memory with manufacturer scan tool; note freeze frame and any related codes
- Visual inspection: coolant level, radiator, hoses, signs of leaks or steam
- Inspect wiring and connectors for ECT sensor, cluster and fan relays; check for corrosion, loose pins, chafing
- Check relevant fuses and relays for continuity and correct operation
- With scan tool, monitor live data: engine coolant temperature (ECT), fan status, and lamp command/DIAGNOSTIC outputs
- Operate cooling fan(s) with scan tool or by applying 12 V to fan connector (bench) to confirm fan operation
Signal parameters
- Engine Coolant Temperature (ECT) sensor: NTC thermistor style — expected behavior: resistance decreases as temperature rises; typical sensor signal to ECU is 0–5 V (varies by design)
- Typical ECT voltage behavior (general reference): cold engine: higher voltage (~>2–4 V depending on design); hot engine: lower voltage (~
- Cooling fan command: ECU/BCM output may be a switched ground, +12 V or PWM signal; fan should run when ECT ≈ 95–110 °C (vehicle dependent)
- Instrument cluster lamp drive: may be direct 12 V/ground drive or a CAN/serial lamp command; check for presence of drive voltage or CAN messages when lamp commanded
- Fuse/relay supply: battery voltage (≈12 V) present at lamp/cluster fuse and fan relay coil when key on
Diagnostic algorithm
- Connect a Renault-compatible scan tool. Record P101E and any related codes (P0115/P0118/P0480 etc.) and freeze frame. Monitor live ECT sensor reading and lamp command while engine cold and during warm‑up.
- Visual inspection: confirm coolant level, inspect for leaks, check radiator cap, hoses, and coolant condition. Repair any leaks before further testing.
- Check fuses and relays for lamp and cooling fan circuits; replace if faulty.
- With ignition on, check for lamp operation via cluster test mode. If lamp does not light in test mode, suspect cluster or supply/ground to cluster.
- Backprobe ECT sensor connector: measure sensor signal voltage or resistance vs ambient temperature and compare to Renault specification. Wiggle harness to check intermittent faults.
- Verify continuity and resistance to ground on lamp ground circuit and 12 V feed to lamp/cluster. Repair any open/shorts/corrosion.
- Command fans ON with scan tool (or apply 12 V carefully) to verify fan(s) operate and draw correct current. Inspect fan relays/fuse circuits.
- If ECT reading is implausible but wiring and power are good, replace ECT sensor and retest.
- If lamp drive signal from ECU is absent or incorrect while ECU reports proper ECT and fan operation is normal, diagnose instrument cluster or BCM and associated CAN/communication signals.
- If all wiring, sensors, fans and cluster test OK, update or reprogram ECU/BCM/cluster software per latest technical service bulletins, or replace faulty module only after confirmation.
Likely causes
- Wiring/connector damage or poor ground to instrument cluster or ECT sensor
- Faulty ECT sensor producing incorrect or no signal to ECU
- Instrument cluster lamp driver failure
- Cooling fan not operating leading to actual over‑temperature and lamp circuit error
- Blown fuse or faulty relay affecting lamp supply
Fault status
Status
P101E — Circuit malfunction detected for the engine coolant 'hot' warning lamp; may indicate electrical fault in lamp/sensor/cluster circuit or a genuine engine over‑temperature condition.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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