P0118 on Toyota: How to Diagnose & Fix
Engine Coolant Temperature Sensor Circuit High
1 Toyota model · 1 documented issue · $100-$2,000 repair
P0118 on Toyota by model: symptoms, diagnosis and fix
The 2023+ Sequoia with the i-FORCE MAX twin-turbo V6 hybrid powertrain has experienced cooling system issues related to the added complexity of cooling both the twin-turbo engine and hybrid battery system. Owners report coolant loss with no visible external leak (internal leak at turbo coolant lines), electric cooling fan running continuously at high speed even in mild weather, and occasional overheating warnings during towing. The hybrid battery cooling circuit is separate from the engine cooling circuit and has its own failure modes.
Common Symptoms
- Coolant level dropping with no visible leak
- Cooling fans running at high speed constantly
- Overheating warning while towing
- Sweet coolant smell from engine bay
- Hybrid system reduced power warning
- Engine temperature gauge reading higher than normal
How to Fix
For coolant loss: have the dealer pressure test both the engine and turbo cooling circuits. Common leak points are the turbo coolant feed/return lines and the intercooler. For continuous fan operation: the hybrid battery cooling fans have an independent control module — check for DTCs related to battery temperature management. For towing overheating: ensure the transmission cooler and auxiliary cooler (if equipped with tow package) are functioning. Toyota has issued TSBs addressing cooling system software calibration. Verify all cooling system software is at the latest version.
Owner tips & cautions
- WarningCheck coolant level weekly during the first year of ownership. The twin-turbo system has many more coolant connections than a naturally aspirated engine. Catching a small leak early prevents overheating damage.
P0118 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0118 mean on a Toyota?
P0118 stands for "Engine Coolant Temperature Sensor Circuit High." P0118 indicates the engine coolant temperature (ECT) sensor circuit is reading abnormally high voltage, which the computer interprets as an implausibly cold coolant temperature. The ECT sensor changes resistance with temperature and tells the PCM how hot the engine is so it can manage fuel, the cooling fans, and the gauge. High voltage on this circuit usually points to an open circuit or a sensor reporting an unrealistically low temperature. The car may run rich, struggle to enter closed-loop operation, idle poorly, or show an inaccurate temperature gauge. On Toyota it is documented across 1 model: Sequoia.
What are the most common causes of P0118?
The most common causes of P0118 are: Faulty (open) engine coolant temperature sensor, Open or broken wire in the ECT signal circuit, Loose, corroded, or disconnected sensor connector, Poor ground or open in the sensor return circuit, Damaged wiring harness near the sensor, Corrosion in the connector terminals, Failed PCM input (rare). The specific cause varies by vehicle.
How much does it cost to fix P0118 on a Toyota?
Published repair estimates on Toyota range from $100 to $2,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0118 on a different make?
View P0118 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.