Genuine OEM 12631279719 - Engine Coolant Temperature Switch

Product Overview

This Genuine OEM 12631279719 engine coolant temperature switch is an original BMW component designed to monitor coolant temperature and trigger cooling system responses in classic BMW models from the 1980s and early 1990s. The switch fits E28 5 Series sedans (528e, 533i, 535i), E23 7 Series sedans (733i), E24 6 Series coupes (633CSi), E30 3 Series sedans (318i, 325, 325e, 325i, 325iX, 325is), and related variants across multiple generations. As a Genuine BMW part, this switch meets factory specifications and is backed by OEM warranty coverage, ensuring reliable cooling system operation and proper engine temperature management.

Symptoms of a Failing Coolant Temperature Switch

• Engine cooling fan runs continuously or fails to engage at appropriate temperatures
• Overheating or erratic coolant temperature gauge readings
• Check engine light or cooling system warning light illumination
• Poor heater performance or inconsistent cabin temperature control
• Coolant leakage around the switch housing

Cross Reference Numbers

This Genuine OEM 12631279719 is equivalent to or replaces the following part numbers: 12-63-1-279-719, 1263127971.

Vehicle Compatibility

This part fits the popular models below. For Fitment Confidence, please use the vehicle selector tool above to verify exact compatibility for your vehicle.

• BMW 528e 2.7 L6 Gas (E28): 1982–1988
• BMW 533i 3.2 L6 Gas (E12): 1983–1984
• BMW 535i 3.5 L6 Gas (E28): 1985–1988
• BMW 633CSi 3.2 L6 Gas (E24): 1982–1984
• BMW 733i 3.2 L6 Gas (E23): 1982–1984
• BMW 318i 1.8 L4 Gas (E30): 1984–1985
• BMW 325 2.7 L6 Gas (E30): 1986–1988
• BMW 325e 2.7 L6 Gas (E30): 1984–1987
• BMW 325es 2.7 L6 Gas (E30): 1986–1987
• BMW 325i 2.5 L6 Gas (E30): 1987–1993
• BMW 325iX 2.5 L6 Gas (E30): 1988–1990
• BMW 325is 2.5 L6 Gas (E30): 1987–1991

This may also fit other applications. Please use the vehicle selector tool to verify fitment.

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Frequently Asked Questions

How do I know if my BMW E30 or E28 coolant temperature switch needs replacement?

The most common sign is a cooling fan that runs continuously or fails to cycle on and off at appropriate intervals. You may also notice erratic coolant temperature gauge readings, overheating under normal driving, or a coolant leak around the switch housing. If your heater blows inconsistently warm or cold, the temperature switch may be unable to signal the heating system properly.

What is the difference between a Genuine OEM switch and an aftermarket alternative?

Genuine OEM parts are manufactured to BMW's original specifications and are the same components used in factory assembly and dealer service. They carry OEM warranty coverage and are engineered to match your vehicle's electrical and mechanical requirements precisely. Aftermarket switches may vary in tolerance and durability; Genuine OEM ensures a perfect fit and reliable long-term performance.

Can I replace the coolant temperature switch myself, or do I need a technician?

Replacement difficulty depends on your vehicle model and engine bay layout. On many E30 and E28 models, the switch is accessible and can be replaced by a competent DIYer with basic hand tools, a drain pan, and coolant. However, you will need to drain some coolant to access the switch safely. If you are uncomfortable working with cooling systems or lack the proper tools, professional installation is recommended to avoid coolant loss or air lock issues.

Will I lose coolant when I replace this switch?

Yes, you will lose some coolant when removing the old switch. The amount depends on where the switch is located and how quickly you can install the new one. Have fresh coolant on hand and be prepared to top off the system after installation. Refer to your service manual for the correct coolant type and fill procedure for your specific BMW model.

Is this switch the same for all E30 3 Series variants, or do different trims use different switches?

This OEM switch (12631279719) fits all E30 3 Series variants covered in the fitment list, including the 318i, 325, 325e, 325i, 325iX, and 325is. However, always verify fitment using the vehicle selector tool for your specific year and engine combination, as some production years or regional variants may have different cooling system configurations.

What should I do after installing the new coolant temperature switch?

After installation, refill the coolant system to the proper level and bleed air from the system per your service manual instructions. Start the engine and allow it to reach operating temperature, then verify that the cooling fan cycles on and off normally and that the temperature gauge reads correctly. Check for leaks around the switch housing before returning to normal driving.

Order Genuine OEM 12631279719 today. In-stock orders ship same or next business day from our U.S. warehouse, and our fitment team is one call away if you need help confirming the right part for your BMW.

Note: All information on this page and in the FAQ is for general reference only. Verify fitment and consult a professional as needed. eEuroparts.com is not responsible for incorrect part selection or installation.