Engine Temperature Sensor Malfunction in JMC New Boarding

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Engine Temperature Sensor Malfunction in JMC New Boarding

Many JMC new boarding users in Pakistan report irregularities with the engine temperature gauge, such as sudden spikes o r inaccurate readings. What are the common causes of engine temperature sensor failure in JMC vehicles, and what diagnostic steps o r replacements are recommended to resolve this issue effectively?

Talha Kyanii asked on 29 Nov 2025 13:23:14 pm

1 Answer

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Gari Master - on 29 Nov 2025 13:27:43 pm

The coolant engine temperature sensor — which monitors engine temperature and feeds data to the ECU so it can control cooling fan, fuel mixture, ignition timing, etc — can fail o r give incorrect readings if it becomes corroded o r its wiring gets compromised for example due to coolant leakage, moisture, o r heat exposure.
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When the sensor fails, typical symptoms include: erratic temperature gauge readings jumping needle, sudden spikes o r s, engine overheating because the cooling fan may not get triggered, poor fuel efficiency o r excessive fuel consumption, rough idling o r misfires, difficulty starting especially when cold, even black smoke from exhaust due to wrong fuel‑air mixture and activation of the “check‑engine” light.
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JR Sensors
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To diagnose: a mechanic should inspect the sensor physically look for corrosion, damaged connector o r wiring, check coolant leaks, and ideally test the sensor reading with a multimeter/scan tool to see if readings make sense compared to actual engine temperature. Some failures might be intermittent, so symptoms may come and go.

To resolve: if sensor o r wiring is damaged — replace the sensor and connector if needed, repair wiring o r sealing, and ensure coolant system is intact no leaks. Also verify cooling‑fan operation and ECU signals after replacement.