P0117 on Toyota
Engine Coolant Temperature Sensor Circuit Low
P0117 on Toyota vehicles indicates engine coolant temperature sensor circuit low. Au7o has documented this code across 1 Toyota model — most commonly on Prius V. This code means the engine coolant temperature (ECT) sensor is reading too low a voltage, which the computer interprets as an impossibly high coolant temperature. In most cases this is an electrical fault — such as a short to ground in the wiring — rather than the engine actually overheating. The coolant temperature signal affects fuel mixture, cooling fans, and other functions, so a bad reading can cause poor running, hard starting, or fans running constantly. The fault is usually in the sensor or its wiring. Typical repair costs on Toyota range from $250 to $800, depending on the specific model and root cause.
Common Causes of P0117
- •Faulty engine coolant temperature sensor
- •Short to ground in the sensor signal wire
- •Damaged or corroded wiring/connector at the sensor
- •Coolant contamination affecting the sensor
- •Poor electrical ground
- •Faulty PCM/ECM (less common)
P0117 on Toyota by Model
Toyota Prius V(1 issue)
- Electric Water Pump Failure and Engine Overheating2012-2017
The Prius V uses an electric water pump (like all Gen 3 Prius-based vehicles) rather than a belt-driven mechanical pump. The electric pump motor can fail without warning, causing rapid engine overheating. Unlike a belt-driven pump where you'd hear squealing before failure, the electric pump simply stops. The vehicle may overheat within minutes in traffic. Toyota issued a recall for some Prius models but Prius V coverage varies by production date.
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View P0117 across all makes →Frequently Asked Questions
What does P0117 mean on Toyota?▼
P0117 stands for "Engine Coolant Temperature Sensor Circuit Low." This code means the engine coolant temperature (ECT) sensor is reading too low a voltage, which the computer interprets as an impossibly high coolant temperature. In most cases this is an electrical fault — such as a short to ground in the wiring — rather than the engine actually overheating. The coolant temperature signal affects fuel mixture, cooling fans, and other functions, so a bad reading can cause poor running, hard starting, or fans running constantly. The fault is usually in the sensor or its wiring. On Toyota specifically, this code is documented across 1 model.
What causes P0117 on Toyota vehicles?▼
Common causes on Toyota: Faulty engine coolant temperature sensor, Short to ground in the sensor signal wire, Damaged or corroded wiring/connector at the sensor, Coolant contamination affecting the sensor, Poor electrical ground. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0117 on a Toyota?▼
Repair costs on Toyota range from $250 to $800, depending on the specific model and root cause.
Which Toyota models have P0117 documented?▼
Au7o has documented P0117 on 1 Toyota model: Prius V.