Temperature Sensors

Temperature Sensors: the small parts your ECU and fans can't run without

Temperature sensors do one job well: they turn heat into a signal your engine management, gauge or fan controller can read. An air or coolant sensor feeds the ECU so it can trim fueling and timing as conditions change. A thermocouple reads exhaust gas temperature (EGT) so you can watch how hard the engine is working under boost. A fan control sensor simply closes a circuit at a set temperature to switch a cooling fan on and off. Fit the right one and your readings are accurate; fit the wrong one and everything downstream guesses.

What ThreePiece stocks

This category currently lists 15 temperature sensors from 8 brands: SPAL, AEM, Haltech, Mishimoto, GReddy, Smarty, TwinPower and Revel. Prices run from $30 to $178, which is the current range for what's in stock rather than a fixed quote. The range covers several distinct jobs. For EGT there's the Smarty Touch Thermocouple EGT Sensor Kit and Haltech open-tip thermocouples in two lengths, the 37-1/2in HT-010863 and the longer 51in HT-010866. For fan switching, SPAL variable temperature control sensors are offered in a 140-165 degree and a 165-185 degree version for brushless fans. For intake air, the AEM Inlet Air Temperature Sensor Kit for EMS is a common EMS pairing.

How to choose

Start with the measurement. If you want exhaust gas temperature, you need a thermocouple like the Haltech or Smarty units, not a fan switch. The two Haltech thermocouples differ only in probe length, so pick the reach that suits where your bung sits; note both are listed excluding fitting hardware. If you're controlling a fan, the SPAL choice is about switch-on point: the 140-165 degree sensor triggers cooler, the 165-185 degree runs a bit hotter before the fan spins. For a standalone or EMS setup wanting intake air data, the AEM kit is the direct answer. Higher price here generally reflects a complete kit rather than a bare probe, so read whether hardware is included before you buy.

What else you need with it

A thermocouple needs somewhere to thread in, so plan for adapters and fittings to mount the probe and route it cleanly. If the sensor is part of a cooling upgrade, pair it with a new radiator. A fan controller sensor works alongside the rest of your engine build, so browse related oil filters and gasket kits while you're in the Engine Components section.

Fitment and ordering

Fitment data here is limited: only one product lists vehicle coverage, sampling Harley-Davidson Touring and Dyna models across roughly 1999-2017. Most of these sensors are chosen by measurement type and thread rather than by vehicle, so confirm the probe, connector and mounting before ordering. If you're unsure which sensor fits your setup, call fitment help at 813-535-5801 or reach us through contact us. All orders ship free, and Affirm and Katapult financing is available.

Temperature Sensors: the small parts your ECU and fans can't run without

Temperature sensors do one job well: they turn heat into a signal your engine management, gauge or fan controller can read. An air or coolant sensor feeds the ECU so it can trim fueling and timing as conditions change. A thermocouple reads exhaust gas temperature (EGT) so you can watch how hard the engine is working under boost. A fan control sensor simply closes a circuit at a set temperature to switch a cooling fan on and off. Fit the right one and your readings are accurate; fit the wrong one and everything downstream guesses.

What ThreePiece stocks

This category currently lists 15 temperature sensors from 8 brands: SPAL, AEM, Haltech, Mishimoto, GReddy, Smarty, TwinPower and Revel. Prices run from $30 to $178, which is the current range for what's in stock rather than a fixed quote. The range covers several distinct jobs. For EGT there's the Smarty Touch Thermocouple EGT Sensor Kit and Haltech open-tip thermocouples in two lengths, the 37-1/2in HT-010863 and the longer 51in HT-010866. For fan switching, SPAL variable temperature control sensors are offered in a 140-165 degree and a 165-185 degree version for brushless fans. For intake air, the AEM Inlet Air Temperature Sensor Kit for EMS is a common EMS pairing.

How to choose

Start with the measurement. If you want exhaust gas temperature, you need a thermocouple like the Haltech or Smarty units, not a fan switch. The two Haltech thermocouples differ only in probe length, so pick the reach that suits where your bung sits; note both are listed excluding fitting hardware. If you're controlling a fan, the SPAL choice is about switch-on point: the 140-165 degree sensor triggers cooler, the 165-185 degree runs a bit hotter before the fan spins. For a standalone or EMS setup wanting intake air data, the AEM kit is the direct answer. Higher price here generally reflects a complete kit rather than a bare probe, so read whether hardware is included before you buy.

What else you need with it

A thermocouple needs somewhere to thread in, so plan for adapters and fittings to mount the probe and route it cleanly. If the sensor is part of a cooling upgrade, pair it with a new radiator. A fan controller sensor works alongside the rest of your engine build, so browse related oil filters and gasket kits while you're in the Engine Components section.

Fitment and ordering

Fitment data here is limited: only one product lists vehicle coverage, sampling Harley-Davidson Touring and Dyna models across roughly 1999-2017. Most of these sensors are chosen by measurement type and thread rather than by vehicle, so confirm the probe, connector and mounting before ordering. If you're unsure which sensor fits your setup, call fitment help at 813-535-5801 or reach us through contact us. All orders ship free, and Affirm and Katapult financing is available.