How to check and replace a coolant temperature sending unit on Mercury Mountaineer?

The coolant temperature indicator system consists of a warning light or a temperature gauge on the dash and a coolant temperature-sending unit mounted on the engine. On the models covered, the Cylinder Head Temperature (CHT) sensor (V8 models)or Engine Coolant Temperature (ECT)sensor(V6 models), which is an information sensor for the Powertrain Control Module (PCM), also functions as the coolant temperature sending unit. If an overheating indication occurs check the coolant level in the system and make sure all connectors in the wiring harness between the sending unit and the indicator light or gauge are tight. When the ignition switch is turned to start and the starter motor is turning, the indicator light (if equipped) should come this doesn't mean the engine is overheated; it just means that the bulb is good. If the light doesn't come on when the ignition key is turned to START the bulb might be burned out, the ignition switch might be faulty or the circuit might be open. As soon as the engine starts, the indicator light should go out and remain off, unless the engine overheats. if the light doesn't go out, the wire between the sending unit and the light could be grounded, the sending unit might be defective, or the ignition switch might be faulty. Check the coolant to make sure it's correctly mixed; plain water. with no antifreeze, or coolant that's mainly water, might have too low a boiling point to activate the sending unit.

Genuine Mercury Mountaineer Coolant Temperature Sensor

Coolant Water Temperature Sensor

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7 Coolant Temperature Sensors found

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Mercury Mountaineer Sender Assembly - Temperature
Part Number: F7DZ-10884-AA
$13.73 MSRP: $27.27
You Save: $13.54 (50%)
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Product Specifications
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 1997-2001 Mercury Mountaineer | 6 Cyl 4.0L, 8 Cyl 5.0L | 4AT 4R70W, 5AT 5R55E
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Mercury Mountaineer Sender Assembly
Part Number: 1L2Z-12A648-AA
$35.25 MSRP: $48.16
You Save: $12.91 (27%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Sender Assy
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2002 Mercury Mountaineer | 6 Cyl 4.0L SOHC EFI | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)
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Mercury Mountaineer Sender Assembly - Temperature
Part Number: F1SZ-10884-A
$34.54 MSRP: $55.09
You Save: $20.55 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Sender Assy - Temperature
- Replaces: DOWY-10884-A
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 1997-2001 Mercury Mountaineer | 6 Cyl 4.0L, 8 Cyl 5.0L | 4AT 4R70W, 5AT 5R55E
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Mercury Mountaineer Sender Assembly
Part Number: F5AZ-12A648-AB
$25.76 MSRP: $41.09
You Save: $15.33 (38%)
Ships in 1 Business Day
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Product Specifications
- Other Name: Sender Assy
- Replaced by: 3F1Z-12A648-A
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2006-2010 Mercury Mountaineer | 8 Cyl 4.6L | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)
View related parts
Mercury Mountaineer Sender Assembly
Part Number: 3L8Z-12A648-A
$29.64 MSRP: $47.27
You Save: $17.63 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Sender Assy
- Replaces: 3L8Z-12A648-BA, DY-1004
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2002-2010 Mercury Mountaineer | 6 Cyl 4.0L SOHC EFI | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)
View related parts
Mercury Mountaineer Sender Assembly
Part Number: F8CZ-12A648-B
$17.78 MSRP: $28.36
You Save: $10.58 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Sender Assy; Coolant Temperature Sensor, Temperature Sensor
- Replaces: F77Z-12A648-AA, F8CZ-12A648-AA, DY-824
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 2006-2010 Mercury Mountaineer | 6 Cyl 4.0L SOHC EFI | 5-Speed Automatic Transmission 5R55S, 5-Speed Automatic Transmission 5R55W, 5-Speed Manual Transmission (M5R4), 6-Speed Automatic Transmission (6R80), 6-Speed Automatic Transmission 6R60, Four-Wheel Drive (Full Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Left Hand Drive), Four-Wheel Drive (Part Time) (Right Hand Drive), Left Hand Drive, Rear-Wheel Drive (Left Hand Drive)
- 1998-2001 Mercury Mountaineer | 6 Cyl 4.0L | 4AT 4R70W, 5AT 5R55E
View related parts
Mercury Mountaineer Sender Assembly
Part Number: F77Z-12A648-AA
$17.78 MSRP: $28.36
You Save: $10.58 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Sender Assy
- Replaced by: F8CZ-12A648-B
- Warranty: This genuine part is guaranteed by Ford's factory warranty.
Fits the following Vehicles:
- 1998-2001 Mercury Mountaineer | 6 Cyl 4.0L | 4AT 4R70W, 5AT 5R55E

Mercury Mountaineer Coolant Temperature Sensor Parts Questions & Experts Answers

Sender Assembly
F8CZ-12A648-B
Q: How to check and replace a coolant temperature sending unit on Mercury Mountaineer?
A: The coolant temperature indicator system consists of a warning light or a temperature gauge on the dash and a coolant temperature-sending unit mounted on the engine. On the models covered, the Cylinder Head Temperature (CHT) sensor (V8 models)or Engine Coolant Temperature (ECT)sensor(V6 models), which is an information sensor for the Powertrain Control Module (PCM), also functions as the coolant temperature sending unit. If an overheating indication occurs check the coolant level in the system and make sure all connectors in the wiring harness between the sending unit and the indicator light or gauge are tight. When the ignition switch is turned to start and the starter motor is turning, the indicator light (if equipped) should come this doesn't mean the engine is overheated; it just means that the bulb is good. If the light doesn't come on when the ignition key is turned to START the bulb might be burned out, the ignition switch might be faulty or the circuit might be open. As soon as the engine starts, the indicator light should go out and remain off, unless the engine overheats. if the light doesn't go out, the wire between the sending unit and the light could be grounded, the sending unit might be defective, or the ignition switch might be faulty. Check the coolant to make sure it's correctly mixed; plain water. with no antifreeze, or coolant that's mainly water, might have too low a boiling point to activate the sending unit.