Frayed or chafed wiring in the ECT sensor circuit, often near the intake manifold or exhaust heat; Corroded or loose connector terminals at the ECT sensor or PCM; Failing ECT sensor that breaks down internally when hot or cold; Coolant contamination or low coolant level causing the sensor to read air pockets; PCM connector pins that are pushed back or corroded, especially on older Ford trucks and SUVs; Aftermarket alarm or remote start wiring that taps into the sensor circuit

DTC codes / Ford codes / P1117

P1117 · FordEngine Coolant Temperature Sensor Intermittent

Q: What does code P1117 mean?

Engine Coolant Temperature Sensor Intermittent. P1117 on Ford vehicles means the powertrain control module (PCM) has detected an intermittent signal from the engine coolant temperature (ECT) sensor circuit. The PCM expects a steady voltage from the ECT sensor that changes smoothly with coolant temperature, and an intermittent drop or spike in that signal sets this code.

P1117 on Ford vehicles means the powertrain control module (PCM) has detected an intermittent signal from the engine coolant temperature (ECT) sensor circuit. The PCM expects a steady voltage from the ECT sensor that changes smoothly with coolant temperature, and an intermittent drop or spike in that signal sets this code.

SystemPowertrain

Code typeFord specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Often no symptoms besides the warning light, especially if the intermittent fault is brief
Cooling fan running constantly or not engaging at all due to faulty temperature data
Poor fuel economy or rough running when the engine is cold because the PCM misjudges enrichment
Erratic temperature gauge readings or a gauge that jumps around
Hard starting or stalling when the engine is cold or hot
Intermittent check engine light that may clear on its own after several drive cycles

Common causes, most likely first

Frayed or chafed wiring in the ECT sensor circuit, often near the intake manifold or exhaust heat
Corroded or loose connector terminals at the ECT sensor or PCM
Failing ECT sensor that breaks down internally when hot or cold
Coolant contamination or low coolant level causing the sensor to read air pockets
PCM connector pins that are pushed back or corroded, especially on older Ford trucks and SUVs
Aftermarket alarm or remote start wiring that taps into the sensor circuit

How to diagnose and fix it

Inspect the ECT sensor connector and wiring for chafing, corrosion, or loose pins, and repair as needed
Check coolant level and condition, then top off or flush if contaminated
Measure the ECT sensor resistance cold and hot and compare to Ford specifications for your engine
Backprobe the ECT signal wire at the PCM and wiggle the harness to catch an intermittent drop
Check for aftermarket wiring taps near the ECT circuit and remove or repair them
Replace the ECT sensor if resistance is out of spec or erratic when heated
Clear the code and perform a drive cycle to confirm the repair, then recheck for pending codes

Why an intermittent ECT code misleads

A common miss is a chafed wire behind the intake manifold that only shorts when the engine torques under load, so a stationary wiggle test passes.
The ECT sensor can test fine at room temperature but break down when hot, so always test resistance at operating temperature as well as cold.
Low coolant or air pockets can make the sensor read erratically without any electrical fault, so check the cooling system before replacing parts.
Aftermarket remote start or alarm wiring tapped into the ECT signal is a frequent cause on older Ford vehicles and is easily overlooked.
A failing thermostat that sticks open can cause the ECT signal to change too slowly, which some Ford PCMs interpret as an intermittent fault.

Can I keep driving with P1117?

You can usually drive with this code, but avoid long trips or heavy loads until it is fixed because faulty temperature data can affect cooling fan operation and fuel mixture. If the temperature gauge is erratic or the engine runs rough, have it checked promptly.

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.