Engine Coolant Temperature Sensor 1 Circuit
Table of contents
- Possible Causes
- How To Fix
- Tech Notes
- Cost To Diagnose
- When is the code detected
- Possible Symptoms
- Description
P0115 MERCEDES-BENZ Possible Causes
- Low engine coolant level
- Faulty Engine Coolant Temperature (ECT) sensor
- Faulty engine coolant thermostat
- Engine Coolant Temperature (ECT) sensor harness is open or shorted
- Engine Coolant Temperature (ECT) sensor circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How do I fix code P0115 MERCEDES-BENZ?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Tech Notes
- Mercedes Benz Code = 0405 (Heating system shutoff valve) has a short circuit to positive. (P0115)
- Mercedes Benz Code = 0406 (Heating system shutoff valve) has a short circuit to ground. (P0115)
- Mercedes Benz Code = 0407 (Heating system shutoff valve) has an open circuit in the wiring. (P0115)
Cost of diagnosing the P0115 MERCEDES-BENZ code
The cost of diagnosing the P0115 MERCEDES-BENZ code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
When is the code detected
An excessively low or high voltage from the sensor is sent to Engine Control Module (ECM).
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0115 MERCEDES-BENZ Description
This fault code is stored in the Engine Control Module (ECM) when the output from the engine coolant temperature sensor is not as expected or missing. The engine control module uses information from the intake air temperature sensor and engine oil temperature sensor to carry out a plausibility check on the signal. Engine coolant temperature sensors are normally a negative temperature coefficient thermistor. The signal voltage drops as the engine coolant temperature increases. The signal from the sensor is used to adjust the ignition system rate of advance and fuel injection system duration for various operating conditions. A faulty engine coolant temperature sensor may result in an engine over fuelling or not entering closed loop control. The rate of ignition advance is reduced when the engine is hot to reduce the possibility of engine knock occurring.