Engine Coolant Temperature Sensor Guide for the 2011-2016 BMW 740i
Experiencing overheating, poor fuel economy, or a check engine light on your BMW 740i? Your coolant sensor might be the culprit.
- A bad coolant sensor can cause overheating, poor fuel economy, and a check engine light.
- Replacement is a simple, DIY-friendly job that takes less than an hour.
- Choose a quality aftermarket brand like Delphi or Beck Arnley for reliability.
- Check if the separate, critical water pump recall (NHTSA 24V-608) has been performed on your vehicle.
Is Your 740i's Coolant Temp Sensor Failing?
A faulty Engine Coolant Temperature (ECT) sensor can cause a range of confusing problems for your BMW. Because the sensor's reading affects so many other systems, a bad signal can make the car behave erratically. If the sensor sends a false 'cold' signal, the engine may run too rich, hurting fuel economy and potentially causing black smoke from the exhaust. If it sends a false 'hot' signal, or no signal at all, the cooling fans may not turn on when needed, leading to overheating. This can put your engine at risk of serious damage.
Important Note on a Related Recall
While there are no specific recalls for the coolant temperature sensor on the 740i, there is a significant safety recall (NHTSA Campaign: 24V608) for the electric water pump on many 2011-2018 BMWs, including models with similar engines. This issue involves a connector that can short circuit, posing a fire risk. It is critical to ensure this separate recall has been addressed for your vehicle, as the water pump is a key part of the cooling system.
Choosing the Right Aftermarket Sensor
When replacing the ECT sensor, you don't always have to buy an expensive OEM part from the dealer. Several reputable aftermarket brands offer quality replacements. Based on owner feedback and brand reputation, aftermarket options can be grouped into tiers.
- Premium Aftermarket (Closer to OEM): Brands like Delphi and Beck Arnley are often well-regarded in the BMW community. Delphi is a known OEM supplier for many manufacturers, and their parts are engineered to meet high standards. Beck Arnley specializes in sourcing parts that match original equipment form, fit, and function.
- Standard Aftermarket: Brands like Vemo, Standard Ignition (SMP), and NGK also produce reliable sensors. These offer a good balance of quality and cost for most owners.
- Value-Oriented Options: Other brands available will function correctly but may not have the same long-term durability or precise calibration as premium options. For a critical sensor like this, investing a few extra dollars in a more reputable brand is often wise.
Pro Tip: Quick and Clean Installation
The coolant temperature sensor on the N55 engine in your 740i is located on the cylinder head, near the oil filter housing. 🎬 Watch: See the exact sensor location on N55 engines. When replacing it, have the new sensor ready to install immediately after removing the old one to minimize coolant loss. A small amount of coolant will spill. Always use a new o-ring/seal, which should come with the new sensor, and do not overtighten the part, as it can be easily damaged. After installation, it's a good idea to bleed the cooling system to remove any air that may have entered.
🎬 See this walkthrough for bleeding the N55 cooling system.How Much Should It Cost?
The cost to replace the coolant temperature sensor is relatively low, especially if you do it yourself. The part itself is inexpensive, and labor is minimal.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Sensor | $19 - $69 |
| New OEM Sensor | $70 - $120 |
| Shop Labor | $90 - $180 |
| Total Professional Replacement (Aftermarket) | $109 - $249 |
Frequently Asked Questions
Where is the engine coolant temperature sensor located on my 2011-2016 740i?
The sensor is located on the front of the cylinder head, near the oil filter housing. It is screwed into the head and has an electrical connector attached.
Can I replace this sensor myself?
Yes, this is a very feasible DIY job for someone with basic tools. It requires a 22mm deep socket and care not to overtighten the new sensor. The job can typically be done in under 30 minutes.
What happens if I ignore a bad coolant temperature sensor?
Ignoring a faulty sensor can lead to serious issues. You may experience very poor fuel economy, failed emissions tests, or a no-start condition. Most critically, if the sensor fails to report an overheating condition, you risk severe engine damage like a warped cylinder head or blown head gasket.
My check engine light is on. Could it be this sensor?
Absolutely. A failing coolant temperature sensor is a common cause for the check engine light. A common trouble code associated with this failure is P0128, which indicates the engine coolant temperature is below the thermostat regulating temperature.
🎬 Watch: How to fix a P0128 fault code yourself.Helpful Videos
Technical Specifications
OEM Part Numbers: 13627580635
Location: Cylinder Head, near Oil Filter Housing. Required Tools: 22mm deep socket.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- BMW 740i: