P0128 on a 2017 Ford Edge

P0128 means the engine warmed up slower than expected or stayed cooler than the computer expected.

Not your vehicle? See general P0128 info.

Most common causes on the 2017 Ford Edge

Ranked from 1,300 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Chronic low coolant level from this vehicle's documented coolant-intrusion defect
Medium severity
This exact vehicle has a well-documented internal coolant-intrusion defect (owners repeatedly report empty reservoirs, low-coolant warnings, and even an 'Engine Coolant Over Temperature' event); running chronically low on coolant can produce erratic, out-of-range coolant-temperature readings.
Reported in 4 NHTSA complaints
2
Thermostat replaced during a misdiagnosed coolant-intrusion repair
Low severity
At least one owner's shop replaced the water pump and thermostat as a first guess before the true coolant-intrusion defect was identified, suggesting the thermostat is commonly (and sometimes needlessly) swapped on this vehicle.
Reported in 1 NHTSA complaint
Parts:thermostat
3
Stuck-open thermostat
High severity
The classic cause of a P0128; the engine never reaches its regulating temperature.
Common cause
Parts:thermostat
4
Failed engine coolant temperature (ECT) sensor
Medium severity
A biased ECT sensor reports a falsely low temperature even on a properly warmed engine.
Common cause
Parts:coolant temperature sensor
5
Cooling fan stuck on
Low severity
A fan that runs continuously over-cools the engine.
Common cause
Parts:cooling fan
6
Air pocket in the cooling system after repeated coolant top-offs
Low severity
Owners of this vehicle frequently top off coolant between failures; incomplete bleeding afterward can leave air pockets that skew temperature readings.
Common cause

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0128 on your car still needs shop confirmation before any repair.

Common symptoms

Check engine light
Weak cabin heat
Poor fuel economy
Temperature gauge low
Long warm-up time

What to check before replacing parts

Check coolant level when the engine is cold

Look for: Low coolant reduces the system's ability to reach and hold operating temperature — top off and recheck before assuming the thermostat or sensor is at fault.

Compare scan-tool coolant temperature to actual warm-up time

Look for: An engine that takes noticeably longer than normal to reach operating temperature (or never gets there) on the scan tool, with normal coolant level, points to the thermostat rather than the sensor.

Inspect thermostat operation

Look for: A thermostat stuck open (or opening at the wrong temperature) lets coolant circulate through the radiator too early, keeping the engine running cooler than it should — this is the most common cause of this code.

Check cooling fan command

Look for: A fan that runs constantly or turns on too early (commanded on when temperature is still low) keeps the engine from warming up normally, mimicking a stuck-open thermostat.

Inspect coolant temperature sensor data

Look for: A sensor reading that doesn't rise smoothly with actual engine warm-up, or that reads implausibly low compared to how the engine feels/behaves, points to a sensor or wiring fault rather than a true cooling problem.

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