Engine Coolant Temperature Sensor Circuit Low Input
The engine computer is getting a very low signal from the coolant temperature sensor. This usually means the sensor, wiring, or connector has a problem. It can make the engine run poorly and may cause hard starting, rich running, or fan problems.
You may be able to drive short distances, but the engine may run badly and fuel economy can drop. Do not ignore it, because incorrect coolant temperature readings can cause overheating or other damage if cooling fan control is affected.
P0117 means the powertrain control module has detected a low input voltage from the engine coolant temperature (ECT) sensor circuit 1. On most vehicles, a low voltage signal indicates either a short to ground, a failed sensor, poor connector contact, or damaged wiring, and the PCM interprets this as an abnormally high coolant temperature. The fault can affect fuel mixture, idle quality, cooling fan operation, and cold-start enrichment.
It means the engine coolant temperature sensor circuit is showing a signal that is too low, which usually points to a sensor or wiring fault.
Yes. If the PCM thinks the engine is already hot, it may not add enough fuel for a cold start.
It can on some vehicles. The PCM may use a fail-safe strategy if it does not trust the coolant temperature reading.
Not always. Check coolant level, connector condition, and wiring first because those are common causes.