Faulty engine coolant temperature sensor that is out of specification or slow to respond; Corroded, loose, or damaged wiring and connector pins at the ECT sensor; Open or shorted signal or ground circuit between the ECT sensor and the PCM; Low coolant level or air pockets in the cooling system causing the sensor to read incorrectly; Thermostat stuck open, preventing the engine from reaching the temperature the self-test expects; PCM software calibration issue or a faulty PCM (rare, but possible after other causes are ruled out)

DTC codes / Ford codes / P1116

P1116 · FordEngine Coolant Temperature Sensor is Out of Self-Test Range

Q: What does code P1116 mean?

Engine Coolant Temperature Sensor is Out of Self-Test Range. P1116 on Ford vehicles means the powertrain control module (PCM) ran its self-test of the engine coolant temperature (ECT) sensor circuit and found the signal outside the range the PCM expects during that test. The PCM is not reporting a simple open or short circuit; it is flagging that the coolant temperature reading did not behave as expected during the key-on or start-up self-test window.

P1116 on Ford vehicles means the powertrain control module (PCM) ran its self-test of the engine coolant temperature (ECT) sensor circuit and found the signal outside the range the PCM expects during that test. The PCM is not reporting a simple open or short circuit; it is flagging that the coolant temperature reading did not behave as expected during the key-on or start-up self-test window.

SystemPowertrain

Code typeFord specific

SeverityLow

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or poor driveability when the engine is cold
Incorrect temperature gauge reading or a gauge that stays low
Higher-than-normal fuel consumption because the PCM thinks the engine is cold
Hard starting or a rich-running condition in cold weather
Cooling fan running constantly or not engaging when it should

Common causes, most likely first

Faulty engine coolant temperature sensor that is out of specification or slow to respond
Corroded, loose, or damaged wiring and connector pins at the ECT sensor
Open or shorted signal or ground circuit between the ECT sensor and the PCM
Low coolant level or air pockets in the cooling system causing the sensor to read incorrectly
Thermostat stuck open, preventing the engine from reaching the temperature the self-test expects
PCM software calibration issue or a faulty PCM (rare, but possible after other causes are ruled out)

How to diagnose and fix it

Check coolant level and condition, then pressure-test the cooling system for leaks or air pockets
Inspect the ECT sensor connector and wiring for corrosion, chafing, or loose pins
Measure the ECT sensor resistance with a multimeter and compare it to Ford's temperature-resistance chart
Back-probe the sensor signal circuit at the PCM and compare the voltage to the expected value for the actual coolant temperature
Verify thermostat operation by watching coolant temperature rise to normal operating range during a road test
Replace the ECT sensor if resistance is out of range or it responds too slowly to temperature changes
Clear the code and perform a drive cycle to confirm the self-test passes and the code does not return

Why the self-test range matters on Fords

This code is set during a specific PCM self-test window, so a sensor that reads correctly once the engine is warm can still trigger P1116 if it is slow or skewed during key-on or early warm-up.
A stuck-open thermostat is a common cause that gets missed because the sensor itself tests fine at room temperature; the engine simply never reaches the temperature the self-test expects.
Air pockets from a recent cooling system service can make the ECT sensor read low even when the sensor and wiring are perfect, so bleed the system before condemning parts.
Ford ECT sensors use a negative temperature coefficient (NTC) element, meaning resistance drops as temperature rises; a sensor that is only slightly out of spec can pass a basic ohm check but still fail the self-test.
Do not replace the PCM until you have verified the sensor, wiring, coolant level, and thermostat, because a false P1116 from a cooling system issue will return on a new PCM.

Can I keep driving with P1116?

You can usually keep driving with P1116 because it is a self-test range fault rather than a severe circuit failure, but avoid long trips or heavy load until it is diagnosed. If the temperature gauge behaves erratically or the engine runs poorly when cold, have it checked promptly to prevent rich-running conditions and poor fuel economy.

Tools that help

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Guidance is general and written for Ford vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.