How much does it cost to fix P0118 on a Toyota?

Repair costs for P0118 on Toyota vehicles typically range from $40 to $220 depending on the underlying cause. The most common fix is: Degraded ECT sensor near the thermostat housing, often combined with a corroded or coolant-contaminated connector..

Toyota Check Engine Code

P0118 on Toyota

Engine Coolant Temperature Sensor Circuit High Input

Severity: medium DIY difficulty: 1/5 Toyota cost: $40–$220

Last updated April 30, 2026 Also covers: Lexus, Scion

P0118 on Toyota: what makes it different

Toyota's Engine Coolant Temperature (ECT) sensor is a simple two-wire thermistor mounted near the thermostat housing, and on high-mileage 4-cylinder and V6 engines the sensor or its connector commonly develops a high-resistance fault that the PCM reads as an unrealistically low coolant temperature (hence 'circuit high').

Most-affected engines

1NZ-FE 1.5L (Corolla, Echo)
2AZ-FE 2.4L (Camry, RAV4, Scion)
2GR-FE 3.5L V6 (Camry, Highlander, Sienna)
1AZ-FE 2.0L (various markets)

Common model years: 2003–2013

Most likely cause on Toyota

Degraded ECT sensor near the thermostat housing, often combined with a corroded or coolant-contaminated connector.

Known Toyota engine-family issues

Toyota thermostat housings on 2AZ-FE and similar engines are known to seep coolant over time at the gasket, and that moisture tends to migrate into the nearby ECT connector, causing exactly this kind of circuit-high fault rather than an outright sensor failure.

Toyota-specific causes (most common first)

Failed/drifted ECT sensor on the thermostat housing
Corroded connector pins from a weeping thermostat housing gasket or small coolant seep
Open or chafed wiring between the sensor and PCM (common where the harness runs near the exhaust manifold)
Thermostat housing cracked, allowing coolant to wick into the sensor connector
Aftermarket or incorrect-resistance sensor installed during a prior repair

Toyota-specific diagnostic tip

Before replacing the sensor, unplug the ECT connector and inspect for green/white corrosion or dampness — on Toyota 4-cylinders this is often traced back to a slow coolant seep at the thermostat housing, not the sensor itself.

Symptoms drivers report

Check engine light
Cold-start hard / no-start
Cooling fans running at low temp
Erratic gauge

Typical repair cost on Toyota

Most Toyota owners fix P0118 for between $40 and $220, depending on which underlying cause turns out to be at fault. Start with the most-likely cause for your vehicle — Degraded ECT sensor near the thermostat housing, often combined with a corroded or coolant-contaminated connector. — before throwing parts at it.

Toyota P0118 FAQ

Will P0118 cause my Toyota to overheat?

Not directly — it usually means the PCM is running a fallback 'warm engine' fuel map, which can cause rough cold starts and poor fuel economy, but it's not the same as an actual overheating condition.

Is the ECT sensor expensive on Toyota models?

The sensor itself is inexpensive, typically under $30, but labor can be higher on transverse V6 engines like the 2GR-FE where the housing sits deep in the engine bay.

Can a bad thermostat cause this code?

Indirectly yes — on Toyota engines a leaking thermostat housing gasket is a very common root cause because the coolant seep corrodes the sensor's electrical connector.