P0117: Engine Coolant Temperature Sensor 1 Circuit Low
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Short trips only - the computer thinks the engine is always hot or always cold, and cooling fan logic may misbehave.
Symptoms
- Hard cold starts
- Cooling fans running constantly
- Poor economy
Likely causes, most common first
- Coolant temp sensor shorted internally
- Wiring chafed to ground
- Connector corrosion
Read P0117 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0117 means the coolant temperature signal is stuck reading extremely hot - the electrical signature of a shorted circuit. Everything temperature-dependent follows it: cold-start enrichment, fan control, even transmission behavior on some cars.
The sensor itself is cheap and usually accessible; test by unplugging it - if the reading flips to the opposite extreme, the wiring is fine and the sensor is the fault.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0117
“The ETC warning light came on, then the car slowed down then stalled out and would not crank back up. Upon running a diagnostic, the following error codes displayed; P0420, P0340, P0197, P0117, P1D83, P2181(several codes showing up more than once showing permanent, pending). This also happened before but was taken to the dealership to be repaired but the problem is back again but worse. Me and my family were on the highway at the time of this happening and when this happened previously, I begged Carvana to take this car back as it not safe and it has happened again.”2017 Dodge Journey · Dec 2022
Cars that report P0117 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0117?
Short trips only - the computer thinks the engine is always hot or always cold, and cooling fan logic may misbehave.
How much does it cost to fix P0117?
Typical US repair costs range from $80 for the simplest fix (coolant temperature sensor) to $250 in the worst case. The right number depends on which cause your car has - see the causes list.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.