P0117
Medium SeverityEngine Coolant Temperature Sensor Circuit Low
Cooling System
P0117 — Instant Answer
Engine Coolant Temperature Sensor Circuit Low
Severity: MEDIUM SEVERITY
Meaning: ECT sensor voltage is too low, indicating an impossibly high temperature. Usually a shorted sensor.
Safe to drive? Usually yes with caution, but confirm root cause before long trips.
Estimated repair cost: $10 - $25
Most common causes:
- 1. Shorted ECT sensor (35-45% of cases)
- 2. Short in sensor wiring (10-25% of cases)
- 3. Corroded connector pins (10-25% of cases)
Symptoms
- ⚠️Fans running at max speed constantly
- ⚠️Rich fuel mixture
- ⚠️Check engine light
- ⚠️Temp gauge pegged high
Related Symptoms
Common Causes
How to Diagnose P0117
- 1Disconnect sensor — fans should stop, gauge should change
- 2Measure sensor resistance
- 3Check wiring for shorts to ground
- 4Replace sensor
OEM Procedures for P0117
Engine Coolant Temperature Circuit Low Input Found 11 OEM service manual procedures.
Coolant Temperature Sensor - Removal & Installation
Coolant Temperature Sensor - Removal & Installation
Coolant Temperature Sensor - Removal & Installation
Coolant Temperature Sensor - Removal & Installation
Coolant Temperature Sensor - Removal & Installation
Coolant Temperature Sensor - Removal & Installation
Coolant Temperature Sensor - Removal & Installation
Coolant Temperature Sensor - Removal & Installation
Showing 8 of 11 procedures
OEM Diagnostic Flowchart
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Parts & Tools for This Job
Common parts shoppers buy for P0117 Engine Coolant Temperature Sensor Circuit Low.
Thermostat
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Engine Coolant
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Radiator
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Water Pump
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Coolant Temp Sensor
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OBD2 scanner
Read codes and freeze-frame data before you guess at the fault.
Most diagnostic jobs start with a scan tool and a verified code path.
Check SpecificationsBattery tester
Check cranking and charging health before replacing expensive parts.
A weak battery can mimic alternator or starter problems.
Check SpecificationsMultimeter kit
Confirm voltage, continuity, and sensor power with one simple kit.
A meter is the cheapest way to rule out a bad circuit fast.
Check SpecificationsRelated Resources
Repair guides, symptom pages, and wiring diagrams related to P0117.
OEM Manual Evidence
Browse →PGM-FI DTCS — 2013 Acura MDX 3.7L Eng VIN 2 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowledge Reimagined Home >> Acura >> 2013...
PGM-FI DTCS — 2013 Acura MDX 3.7L Eng VIN YD2 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowledge Reimagined Home >> Acura >> 20...
Engine Control System - Advanced DTCS — 2013 Acura RDX 3.5L Eng VIN 3 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowledge Reimag...
Engine Control System DTCS — 2013 Acura RDX 3.5L Eng VIN 3 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowledge Reimagined Home >...
Related Symptoms
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Open the exact vehicle hub grounded by OEM manual evidence related to P0117.
Related Codes
The ECT sensor circuit has a general malfunction. This sensor tells the ECM how warm the engine is for fuel, timing, and fan control.
ECT sensor voltage is above maximum, reading as extremely cold. Usually an open sensor circuit.
The ECT sensor reading is not changing as expected during warm-up. Either the sensor is lazy or the thermostat is preventing normal warm-up.
Frequently Asked Questions
- Why are my fans always on with P0117?
- The shorted sensor tells the ECM the engine is overheating, so it runs the fans at max. The engine is likely at normal temperature.
- Can P0117 cause overheating?
- No — it makes the ECM think the engine is hot, but actual temperature is fine. However, always verify with an IR thermometer.
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Author & Review
Published by AllOEMManuals, founded by Lyndon Bedford, an automotive technician with 20 years of experience. He owned and operated a mechanic shop in Hurst, Texas from 2014 to 2022 and continues hands-on repair work.
Content may combine manual references, general repair templates, and AI-assisted drafting. Confirm the source, vehicle configuration, and applicability before working. Report corrections through our contact page.
Last updated: 2026-10-29