P1117 Coolant Temperature Sensor Stack for Heat Storage (Secondary)

Category: Powertrain - Fuel/Air Metering
Severity: Check Engine Light
Applies to: Prius with coolant heat storage

What does P1117 mean on a Toyota?

P1117 — Coolant Temperature Sensor Stack for Heat Storage (Secondary). This Toyota-enhanced code applies to Prius with coolant heat storage.

Common causes of P1117

Secondary sensor drift
Coolant loss in the storage loop
Sensor aging
Connector corrosion
ECM fault

How to fix P1117

Check storage loop coolant
Compare primary and secondary readings
Test sensor resistance
Inspect connectors
Replace the faulty sensor