P0118: Engine Coolant Temperature Sensor 1 Circuit High
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Same as P0117 - tolerable briefly, but cold-start behavior and economy suffer.
Symptoms
- Long cranking when cold
- Rich running, fuel smell
- Temperature gauge reading wrong
Likely causes, most common first
- Open circuit - broken wire or unplugged sensor
- Failed sensor
- Corroded terminals
Read P0118 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
P0118 is the open-circuit version of the coolant temp family: the signal reads impossibly cold, so the computer enriches fuel as if every start were an arctic morning. Fuel economy quietly suffers the whole time.
Same diagnosis as P0117, opposite polarity - a multimeter and the resistance chart for your sensor settle it quickly. Replacing on spec without testing works out fine most of the time given the part's price.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Cars that report P0118 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0118?
Same as P0117 - tolerable briefly, but cold-start behavior and economy suffer.
How much does it cost to fix P0118?
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.