P0116: Engine Coolant Temperature Sensor 1 Circuit Range/Performance
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes - but a thermostat stuck open, the most common cause, costs fuel every mile.
Symptoms
- Engine slow to warm up
- Weak cabin heat in winter
- Worse fuel economy than usual
Likely causes, most common first
- Thermostat stuck open
- Coolant temperature sensor drifting
- Low coolant level
- Sensor reading delayed by scale or air pocket
Read P0116 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
P0116 says the coolant temperature reading is plausible but does not behave the way the computer expects - warming too slowly, sitting too low, or disagreeing with the intake air reading after a cold soak. Nine times out of ten the sensor is honest and the thermostat is the culprit.
A thermostat stuck open never triggers a warning light on its own and never leaves you stranded, so it often runs for years. The tell is weak heat from the vents in winter and a fuel economy figure that quietly dropped by a mile or two per gallon. Because the engine never reaches design temperature, it also wears faster.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0116
“The airbag light came on in the dashboard; took the van to local dealer they diagnosed code p0116 2 part repair replacement of lf side air bag assembly and wiring harness replacement which cost over $1100; *tr”2007 Toyota Sienna · Aug 2012 · 116,000 mi
“Transmission issue? Hard clunk/jerk when approaching highway speed. Happens intermittently without throwing a code. Feels like it's trying to shift down into a low gear for no reason. So far the problem has been quick to resolve right after it occurs. No error codes. It has done this a handful of times. One time it went into limp mode and there was a code p0116 for a transmission coolant temperature sensor. The sensor was replaced but the problem persists without a tripping a code.”2017 Ford F-150 · Dec 1969
Cars that report P0116 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0116?
Yes - but a thermostat stuck open, the most common cause, costs fuel every mile.
How much does it cost to fix P0116?
Typical US repair costs range from $100 for the simplest fix (thermostat) to $500 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0116. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.