- Vehicles
- Cars
P0117
P0117 (generic OBD-II): coolant temperature sensor circuit low input
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
The engine computer gets a voltage outside the possible range from the coolant temperature sensor (low input). It is a circuit fault, not a temperature reading. Watch the temperature gauge: if it rises or there is an overheating warning, stop.
Safety first
Stop and check this first
- If a high temperature warning appears, stop and switch off; do not open the cooling system while hot.
Safe checks you can perform
- Temperature gauge on the cluster
- Coolant level when cold
- Temperature the engine computer sees
Leave these tasks to a qualified professional
- Do not attempt this professional task: Circuit and sensor measurement
- Do not attempt this professional task: Wiggle test and verification
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Circuit and sensor measurement
What they doThe technician measures reference voltage, ground and sensor signal with a multimeter, and the sensor resistance at a known temperature.
They must show youthe measured voltages and resistance against the manufacturer's specification.
In writingwhether a wire or connector is repaired or the sensor replaced, and the part number.
Wiggle test and verification
What they doWith live data, the technician moves the harness and connector looking for jumps in the reading and, after the repair, checks the temperature rises steadily as the engine warms.
They must show youthe live temperature graph during the test and after the repair.
In writingthe cause found and that the code has not returned.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Temperature gauge on the cluster
- Who:
- you, driving carefully or with the engine idling.
- How:
- watch the engine temperature gauge or warning and the radiator fan.
- Result that matters:
- whether there is an overheating warning or the needle reaches red.
- If there is a warning or the needle climbs:
- stop somewhere safe and switch off; do not open the coolant cap while hot.
- If the temperature looks normal:
- the fault is probably electrical; book a visit and keep an eye on the gauge.
- Evidence to keep:
- a photo of the cluster and the temperature needle.
Never open the coolant reservoir with a hot engine: it comes out under pressure and burns.
Evidence: Ford 2020-2023 gasoline OBD system operation
Coolant level when cold
- Who:
- you, with the engine cold and off.
- How:
- check the expansion tank level is between the marks, without opening the cap unless the engine is cold.
- Result that matters:
- whether the level is below minimum.
- If it is low:
- there is a loss as well as the code; tell the workshop and avoid long trips until it is checked.
- If it is fine:
- this points to a sensor circuit fault; the workshop measures wiring and sensor.
- Evidence to keep:
- a dated photo of the level.
Evidence: Ford 2020-2023 gasoline OBD system operation
Temperature the engine computer sees
- Who:
- you, with a generic OBD-II reader and the car parked.
- How:
- read the codes and, if the reader shows live data, check coolant temperature with a cold engine.
- Result that matters:
- whether the reading is impossible for a cold engine (far below or above the outside temperature).
- If the reading is impossible:
- this confirms a circuit or sensor fault.
- If the reading looks real:
- the fault may be intermittent; the workshop should move the wiring while measuring.
- Evidence to keep:
- a photo of the code, the freeze frame and the live temperature.
Use the reader with the car parked and do not clear the code.
Evidence: Ford 2020-2023 gasoline OBD system operation
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Vehicles
- Brand
- OBD-II genérico
- Product type
- Cars
Known code variants
- P0117
- P0117 coolant temperature sensor low
- P0117 OBD2
- P0117 sensor temperatura refrigerante
What it means
P0117 is the generic code for a low input from the engine coolant temperature sensor circuit. In Ford's OBD summary the check runs continuously and sets the fault when the sensor voltage stays below the possible electrical range for a few seconds. A low voltage usually means a short to ground in the wire or sensor. Many other Ford monitors use this temperature, so the code can drag others along with it.
Warnings and stop conditions
- Higheditorial warning
If a high temperature warning appears, stop and switch off; do not open the cooling system while hot.
Evidence: Ford 2020-2023 gasoline OBD system operation
Symptoms and causes
Probable causes · in order
- Wire or sensor shorted to groundPossible
A chafed wire touching ground or a shorted sensor leaves the signal at the low end. It shows when wiring insulation is measured.
Evidence: Ford 2020-2023 gasoline OBD system operation
- Faulty temperature sensorPossible
If wiring and supply are fine, the sensor may be off its curve. It is confirmed by measuring its resistance against the manufacturer's table.
Evidence: Ford 2020-2023 gasoline OBD system operation
- Recent engine workPossible
After belt, thermostat or radiator work it is easy to leave the connector poorly seated. It fits if the code appeared after a job.
Evidence: Ford 2020-2023 gasoline OBD system operation
Virtual technician
Does P0117 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Ford 2020-2023 gasoline OBD system operation
Ford Motor Company · 2023 · manual
- 2
Honda 2020 HR-V Owner's Guide - Dashboard details (malfunction indicator lamp)
American Honda Motor Co. · 2020 · manual
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