Engine Coolant Temperature Circuit Low Input
Our emissions expert has put together the following information about the P0117 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.
OBD II Fault Code
- OBD II P0117
Fault Code Definition
The Engine Coolant Temperature Sensor measures the rise and fall of the Engine Coolant Temperature. This provides critical data needed for the Powertrain Control Module (PCM) to control the Air Fuel Ratio, the Ignition Spark Timing, the cooling fans, and many components of the Emissions Control Systems. The Engine Coolant Temperature Sensor converts the coolant temperature into a voltage that is high when the engine is cold and low as the engine warms up. Code P0117 indicates a low voltage input from the Coolant Temperature Sensor to the PCM.
- Check Engine Light will illuminate
- In many cases, no abnormal symptoms may be noticed
- In some cases, the engine may be hard starting and/or get poor fuel economy
Common Problems That Trigger the P0117 Code
- Defective Engine Coolant Temperature Sensor
- Rusty and/or corroded Engine Coolant
- Faulty or corroded Engine Coolant Temperature wiring or connections
- Engine Coolant Temperature Sensor is replaced when the real cause is rusty coolant
- Engine Coolant Temperature Sensor is replaced when the real cause is a poor connection or chafed wiring
- Engine Coolant Temperature Sensor is replaced when the real problem is in the Cooling System