BRAND NEW *OEM Quality* coolant temperature sensor to suit Mazda RX-8 SE17 with the 1.3L 13B-MSP rotary engine from 2003 to 2012.

Temperature gauge reading high or a check engine light on your RX-8? The coolant temperature sensor is a known failure point on the 13B-MSP rotary. Coolant management is critical on the rotary engine, making this a high-priority repair. This is a direct-fit replacement. Same-day dispatch before 12pm from Cranbourne VIC.

TO SUIT

This sensor suits the Mazda RX-8 SE17 with the 1.3L 13B-MSP twin-rotor Wankel engine from 2003 to 2012, covering both the 141kW and 170kW outputs. Full vehicle list in the compatibility table above.

FITMENT CHECK

Coolant temperature management is especially important on the rotary engine - an inaccurate coolant sensor can cause the engine to run lean on cold starts, which accelerates apex seal wear. Confirm the OEM part number on your existing sensor before ordering.

OEM PART NUMBERS

NF02-18-840
B3C8-18-840
B3C818840A
B593-18-840A
N39118840
Y70218840

OTHER PART NUMBERS

V70-72-0003
6PT 009 107-481
ECT-TY-002

PACKAGE INCLUDES

1 x Coolant Temperature Sensor - 2-pin oval connector, M12x1.5mm thread, 19mm spanner size, green socket, with gasket/seal.

ABOUT THIS SENSOR

The coolant temperature sensor on the RX-8 monitors coolant temperature and feeds this data to the ECU, which uses it to control the cold-start fuel enrichment critical to rotary engine health. The 13B-MSP rotary is sensitive to cold-start lean conditions - a faulty coolant sensor that tells the ECU the engine is already warm will cause the engine to run lean from cold, accelerating wear on the rotor tips and apex seals.

COMMON SYMPTOMS OF FAILURE

Inaccurate or erratic temperature gauge reading
Difficult cold starts or flooding
Poor warm-up performance
Increased fuel consumption
Check engine light - codes P0115 P0116 P0117 P0118

MAZDA RX-8 FE 1.3L 13B-MSP Renesis MPFI Rotary 141kW 4sp Auto 4dr Coupe RWD [07/03 – 06/08]
MAZDA RX-8 FE 1.3L 13B-MSP Renesis MPFI Rotary 158kW 6sp Auto 4dr Coupe RWD [07/08 – 07/12]
MAZDA RX-8 FE 1.3L 13B-MSP Renesis MPFI Rotary 170kW 6sp Man 4dr Coupe RWD [07/03 – 07/12]

How do I test a coolant temperature sensor?

The most common test is to measure the sensor resistance with a multimeter at a known coolant temperature and compare against the manufacturer resistance curve. A cold engine (20 degrees C) typically reads 2,000 to 3,000 ohms and drops to around 200 to 300 ohms at operating temperature (90 degrees C). An OBD2 scanner showing a fixed temperature reading that does not change as the engine warms up is also a strong indicator of sensor failure.

Can a faulty coolant temperature sensor cause my engine to overheat?

Indirectly yes. If the sensor reports a lower temperature than actual, the ECU may not activate the cooling fan at the correct time, allowing the engine to overheat. It can also suppress the dashboard warning light, meaning you may not be alerted until the engine is already at a dangerously high temperature. Replace a suspected faulty sensor promptly.

Do I need to drain the coolant to replace the sensor?

Not always - many coolant temperature sensors can be replaced quickly with minimal coolant loss if you work fast and have a replacement ready to thread in immediately. However on some vehicles the sensor location requires partial coolant drainage. Check the sensor position on your specific engine before starting. Always use fresh coolant when topping up after replacement.

What are the symptoms of a faulty coolant temperature sensor?

Symptoms include poor fuel economy, black smoke, engine overheating warning, incorrect temperature gauge reading, hard starting when cold, and rough idle. Fault codes P0115 to P0119 are commonly associated with coolant temperature sensor faults.

Is it safe to drive with a bad coolant temperature sensor?

A faulty coolant temperature sensor can cause the ECU to run rich fuel mixtures and prevent the cooling fan from operating correctly, risking engine overheating. Replace it promptly - it is a low-cost part that can prevent expensive engine damage.

How do I know if my coolant temperature sensor or my thermostat is faulty?

A faulty thermostat typically causes the engine to overheat or never reach operating temperature. A faulty coolant temp sensor causes incorrect gauge readings and running issues but the coolant itself may be at the correct temperature. An OBD2 scanner showing live coolant temp data helps distinguish between the two.

Are there two coolant temperature sensors on my vehicle?

Many vehicles have two sensors - one for the ECU (engine management) and one for the dashboard temperature gauge. They look similar but are not interchangeable. Check your vehicle's service manual or contact us with your vehicle details to confirm which sensor you need.

Identification
SKU	CCS21-29
Brand	Aftermarket OEM Replacement
Part Numbers
Part Number	CCS21
Reference OEM Number	NF02-18-840
Other OEM Numbers	NF02-18-840, B3C8-18-840, B3C818840A, N39118840
Related Part Numbers	CS840, TCS032, TCS120
Trade Part Numbers	V70-72-0003, 6PT 009 107-481, ECT-TY-002
Product Specifics
Sensor Type	ENGINE COOLANT TEMPERATURE SENSOR
Type	Sensor
Features	Direct Fit
Manufacturer Warranty	1 Year
Thread Size	M12x1.5 mm
Spanner Size	19 mm
Number of pins	2 -pin connector
Connector Shape	oval
Housing Colour	Green
Other Details
Note	Always verify fitment using your vehicle's OEM part number.
Unit Of Measure	ea