The Mercury Temp Sensor (OEM Part #13536A13) is a key component in managing engine temperature across a wide range of Mercury 2-stroke outboards. It delivers real-time temperature data to either analog gauges on carbureted models or the Electronic Control Module (ECM) on later EFI and performance engines.
 
Accurate temperature monitoring is critical to prevent overheating, which can cause severe damage such as warped heads, blown gaskets, or piston failure. When temperatures rise beyond safe limits, the sensor alerts the ECM, prompting automatic adjustments to ignition timing, fuel delivery, and engine RPM. In extreme cases, it activates protection mode to reduce power and prevent further harm.
 
The sensor’s role goes beyond alerting; it helps optimize engine behavior based on thermal inputs, ensuring efficiency and preventing detonation under high loads. A failed sensor may cause inaccurate readings, triggering false alarms or hiding real overheating issues—both of which can shorten engine life or lead to costly repairs.
 
Mercury’s original part number for this sensor is 13536A13. Equivalent and cross-referenced replacements include 8M6000636, 18-5896 (Sierra), 133536A13, 1365-3536A13, and 84-3536A13. These options offer flexibility for servicing older engines, but compatibility should be confirmed by serial number or model reference to ensure proper fit.
 
This sensor is found on Mercury outboards from 135HP to 300HP, including 2.0L, 2.4L, 2.5L, and 3.0L blocks. Common models include the 135, 150, 175, 200, 225 Pro Max, and 260 ROS. Its presence in EFI and high-performance motors makes it essential for both recreational and competitive use.
 
Replacement is straightforward. The sensor mounts in the cylinder head or near the thermostat and is secured with a 5/16-inch bolt. After unplugging the connector, the new sensor is installed with care to reconnect all Tan/Blue-striped wires and the black ground lead using insulated marine-grade terminals. After installation, the engine should be run and monitored to confirm accurate readings.
 
Regular inspection is vital, particularly in saltwater environments where corrosion can impact function. Symptoms like inconsistent gauge readings, frequent alarms, or visible wiring damage suggest the sensor may need replacement. Testing resistance with a multimeter across different temperatures can help verify sensor accuracy.
 
Using a genuine Mercury OEM sensor like the 13536A13 ensures precise calibration and durability. While aftermarket units exist, OEM parts are designed to meet Mercury's performance standards, offering reliability for long-term use in critical engine systems.
 
Includes one (1) Mercury OEM Head Temp Sensor  13536-A13
 
For technical support contact: Mike Hill at mike@buckshotracing77.com or call +1-714-697-1716