P0117 on Mercedes-Benz: Symptoms, Causes & Fix
Official technical diagnostic wire for fault code P0117 specifically affecting Mercedes-Benz vehicles (C-Class, E-Class, S-Class, GLC, GLE).
Select Your Mercedes-Benz Model for P0117:
1. Common Symptoms on Mercedes-Benz Vehicles
When Mercedes-Benz Engine Control Modules (ECM) trigger fault code P0117, drivers typically report:
2. Root Causes on Mercedes-Benz Engines
Historical diagnostic claims across Mercedes-Benz engines point to the following failure distribution:
3. Step-by-Step Fix Protocol for Mercedes-Benz
Read ECT live PID on scanner. If it reads 284°F (140°C) or higher with engine cold, a short to ground exists. on Mercedes-Benz engines.
Unplug sensor connector while watching live data. If temperature drops to -40°F (-40°C), the sensor itself is shorted. on Mercedes-Benz engines.
If reading stays pegged at max with sensor unplugged, inspect harness for pinch points grounding against engine block. on Mercedes-Benz 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 Mercedes-Benz engines.
Bleed air from cooling system, clear DTCs, and verify normal temperature rise on live data. on Mercedes-Benz engines.
Equipment for Diagnosing Mercedes-Benz (P0117)
VVT Oil Control Solenoid Valve
Restores accurate camshaft timing and oil pressure regulation on Mercedes-Benz.
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. Mercedes-Benz P0117 Frequently Asked Questions
What does code P0117 mean on a Mercedes-Benz?
On Mercedes-Benz 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 Mercedes-Benz 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 Mercedes-Benz powertrains, we recommend scanning live data values promptly to prevent secondary damage.
How much does it cost to fix code P0117 on a Mercedes-Benz?
Estimated DIY parts cost ranges from $80 - $250 (DIY: $20 - $60), while professional shop repairs at an authorized Mercedes-Benz dealership or independent specialist typically range from $180 to $380 including diagnostic labor.