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PEX Aftermarket Temperature Sensors

Purpose and Function:

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Temperature sensors monitor the operating temperature of critical engine and vehicle systems to protect components, optimize performance, and ensure safe operation. In heavy-duty vehicles, these sensors include:

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  • Engine Coolant Temperature (ECT) Sensors – monitor coolant to prevent overheating and manage fuel injection.

  • Exhaust Gas Temperature (EGT) Sensors – monitor exhaust for turbo, DPF, and SCR protection.

  • Engine Oil Temperature Sensors – ensure proper lubrication and protect against oil breakdown.

  • Transmission or DEF tank temperature sensors – monitor fluid or urea temperatures for proper operation.

 

They provide real-time feedback to the ECU or vehicle control modules for engine protection, emissions control, and efficiency optimization.

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Features & benefits

  • Prevents engine and component damage due to overheating or low-temperature operation.

  • Optimizes combustion, emissions, and fuel efficiency by providing accurate data for ECU adjustments.

  • Supports aftertreatment protection, e.g., limiting DPF regeneration or SCR dosing if temperatures exceed safe thresholds.

  • Durable construction suitable for extreme heavy-duty conditions: high heat, vibration, and corrosive fluids.

  • Enables predictive maintenance by logging temperature trends and alerting drivers before failures occur.

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Technical Highlights

  • Signal types:

    • Thermistor (resistive): Resistance changes with temperature; common in ECT and oil sensors.

    • Thermocouple (voltage-based): Generates millivolt signal proportional to temperature; used in EGT and high-temperature applications.

    • PTC/NTC sensors: Positive or negative temperature coefficient resistors for specialized monitoring.

  • Placement & range:

    • Coolant: typically 70–120°C.

    • Engine oil: typically 50–150°C, depending on engine type.

    • Exhaust: up to 1,000°C for turbo, DPF, and SCR monitoring.

  • Accuracy & response: Rapid response required in exhaust and oil sensors for real-time control; coolant sensors may have slightly slower response.

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Diagnostic and Testing Tips

  • Visual inspection: Check sensor body, wiring, connectors, and protective sleeves for damage, corrosion, or heat stress.

  • Resistance or voltage test: Compare sensor readings with OEM specifications at a known temperature (e.g., coolant in cold/hot state).

  • Live scan check: Use a diagnostic tool to monitor temperature readings under engine idle, load, and high-temperature conditions.

  • Functional test: For EGT, verify signal changes during acceleration or DPF regeneration; for coolant/oil, ensure readings rise smoothly with engine warm-up.

  • Replace sensors that fail to respond, report erratic readings, or show open/short circuits.

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Installation Tips and Common Issues

  • Ensure sensors are fully seated and torqued per OEM spec to prevent leaks or inaccurate readings.

  • Route wiring away from high heat or moving parts; use protective sleeves as needed.

  • Avoid contamination with coolant, oil, exhaust soot, or other chemicals that may damage the sensing element.

  • Intermittent faults are often caused by connector corrosion or wiring damage, not sensor failure.

  • Some high-temperature EGT sensors require periodic inspection or replacement after prolonged exposure to prevent drift or failure.

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