P0116: The engine coolant temperature reading does not make sense for how the engine is running
Engine coolant temperature (ECT) sensor range/performance problem
Severity: Monitor
A coolant temperature reading that is off can make the mixture run lean or rich; it is a fault to fix soon, but not unsafe by itself unless the engine is really overheating.
It gets more serious if:
- Inspect soon: Inspect soon if the temperature gauge reads hot or the engine overheats; TroubleCodes.net lists an overheated engine as a cause and says to check coolant level, radiator cap and fan operation.
P0116 in short
P0116 means the coolant temperature sensor reading is out of range for what the computer expects. A failed sensor, wiring or connector fault, or a real cooling problem such as an overheated engine can set it. Compare the scan-tool temperature with actual coolant temperature, and check coolant level, cap and fan.
The engine coolant temperature (ECT) sensor tells the computer how hot the engine is, and it uses that to adjust fuel mixture and other functions. P0116 is a range or performance code: the reading is not plausible for the conditions.
TroubleCodes.net lists a defective sensor or high resistance in its wiring, a short to ground on the signal circuit, damaged connectors, loose terminals, an overheated engine, and rarely the computer. It notes the test will not run if intake air temperature sensor faults are stored.
Its advice is to compare the actual coolant temperature with the scan-tool reading, which should agree within about 10 °F (5 °C), then verify radiator cap pressure, coolant level and cooling fan operation before testing the sensor's resistance.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Defective coolant temperature sensor or high resistance in its wiring
Common general cause- Why it ranks here
- This is the first cause listed, and the code is about the sensor's reading being implausible.
- What would change this
- A scan-tool reading that disagrees with the real temperature by more than about 10 °F raises it.
Cause 2: Damaged wiring, connectors or loose terminals
Common general cause- Why it ranks here
- TroubleCodes.net lists short to ground on the signal circuit, faulty connectors and loose terminals.
- What would change this
- A damaged or corroded connector, or a shorted signal wire, raises it.
Cause 3: Overheated engine or cooling system problem
Possible — needs testing- Why it ranks here
- An overheated engine is listed, and the page says to check coolant level, radiator cap pressure and fan operation.
- What would change this
- Low coolant, a weak cap or a fan that does not run raises it.
Cause 4: Engine computer fault
Possible — needs testing- Why it ranks here
- The computer is listed as unlikely.
- What would change this
- Consider it only after everything else tests good.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Compare the coolant temperature on a scan tool with the actual engine temperature measured another way.
IfThe two readings differ by more than about 10 °F (5 °C)
It meansThe sensor or its circuit is giving a wrong reading.
IfThey agree
It meansThe fault may be intermittent; check the wiring.
Step 2: With the engine cold, check the coolant level and radiator cap, then check that the cooling fan runs when the engine is hot.
Warning:Never open the radiator cap on a hot engine; scalding coolant can spray out. Keep hands clear of the fan, which can start on its own.
IfCoolant is low, the cap is weak or the fan does not run
It meansA real cooling problem is likely.
IfThe cooling system checks out
It meansTest the sensor.
Step 3: Measure the sensor's resistance at several temperatures and compare it with the manufacturer's values.
IfResistance is out of specification
It meansThe sensor is at fault.
Points to: Defective coolant temperature sensor or high resistance in its wiring
IfResistance is correct
It meansCheck the wiring and connectors.
Symptoms
- Check engine light
- Poor fuel economy, possibly with rich-mixture codes
- Surging or hesitation when accelerating, from a lean mixture
- Temperature gauge reads hot or the engine overheats Gets more serious: stop and have it checked.
Compare with: Check engine light with loss of power
How to fix
Step 1: With the engine cold, check the coolant level.
Step 2: Look at the coolant temperature sensor connector for corrosion or damage.
Parts and cost context
- Engine coolant temperature (ECT) sensor:Confirm the reading against actual temperature before replacing the sensor. Labour varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
We don't have reviewed vehicle-specific evidence for P0116 yet. The causes and tests above apply across vehicles.
Related codes
No curated relationships for P0116 yet.
P0116 questions
Can P0116 mean the engine is overheating?
Sometimes. An overheated engine is a listed cause, so compare the scan-tool reading with actual temperature and check coolant level, cap and fan.
Sources and review
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error