P0117 on Subaru: Symptoms, Causes & Fix
Official technical diagnostic wire for fault code P0117 specifically affecting Subaru vehicles (Outback, Forester, Crosstrek, WRX, Ascent).
Select Your Subaru Model for P0117:
1. Common Symptoms on Subaru Vehicles
When Subaru Engine Control Modules (ECM) trigger fault code P0117, drivers typically report:
2. Root Causes on Subaru Engines
Historical diagnostic claims across Subaru engines point to the following failure distribution:
3. Step-by-Step Fix Protocol for Subaru
Read ECT live PID on scanner. If it reads 284°F (140°C) or higher with engine cold, a short to ground exists. on Subaru engines.
Unplug sensor connector while watching live data. If temperature drops to -40°F (-40°C), the sensor itself is shorted. on Subaru engines.
If reading stays pegged at max with sensor unplugged, inspect harness for pinch points grounding against engine block. on Subaru engines.
Allow engine to cool, unscrew old ECT sensor from coolant crossover pipe or thermostat housing, install new OEM sensor with fresh thread sealant. on Subaru engines.
Bleed air from cooling system, clear DTCs, and verify normal temperature rise on live data. on Subaru engines.
Equipment for Diagnosing Subaru (P0117)
VVT Oil Control Solenoid Valve
Restores accurate camshaft timing and oil pressure regulation on Subaru.
AstroAI Auto-Ranging Digital Multimeter
Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.
BlueDriver Bluetooth Pro OBDII Scan Tool
Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.
4. Subaru P0117 Frequently Asked Questions
What does code P0117 mean on a Subaru?
On Subaru vehicles, P0117 indicates that the Engine Control Module (ECM) detected engine coolant temperature sensor 1 circuit low. This typically points to ECT sensor internal short to ground or Short circuit to ground in ECT signal wiring harness.
Can I continue driving my Subaru with code P0117?
No. The ECU thinks the engine is at 280°F+ (overheating) and runs rich or disables cooling fan logic. Because this code carries a High severity rating on Subaru powertrains, we recommend scanning live data values promptly to prevent secondary damage.
How much does it cost to fix code P0117 on a Subaru?
Estimated DIY parts cost ranges from $80 - $250 (DIY: $20 - $60), while professional shop repairs at an authorized Subaru dealership or independent specialist typically range from $180 to $380 including diagnostic labor.