P0115: The engine computer sees a signal from the coolant temperature sensor circuit that is outside the expected range
Engine coolant temperature sensor circuit fault
Severity: Inspect soon
TroubleCodes.net warns that overheating that goes unaddressed after this code can cause serious engine damage, so check the cooling system soon.
It gets more serious if:
- Stop: Stop driving if the temperature gauge climbs toward hot or a coolant warning shows. Running an overheated engine can cause severe damage.
P0115 in short
P0115 means the engine computer got a signal from the coolant temperature sensor circuit that is outside the range it expects. Wiring faults and a bad sensor are the usual causes, and low coolant or a thermostat problem can also play a part. Check the coolant level when the engine is cold and get it checked soon.
The computer uses the coolant temperature sensor to time fuel, control the cooling fans and decide when the engine is warm. If the sensor voltage falls outside what the computer expects, it sets P0115.
TroubleCodes.net says the light may be the only sign at first. Because the computer may then run the fans or fuel wrongly, an unresolved fault can let the engine overheat.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Damaged, shorted or corroded sensor wiring or connector
Common general cause- Why it ranks here
- TroubleCodes.net lists wiring and connector damage first among the causes.
- What would change this
- Rises if the connector is corroded or the harness is damaged. Falls if wiring tests good.
Cause 2: Failed coolant temperature sensor
Common general cause- Why it ranks here
- A defective sensor is the next cause listed, and it is confirmed by checking its resistance as it warms.
- What would change this
- Rises if sensor readings do not rise smoothly as the engine warms. Falls if readings track a real thermometer.
Cause 3: Low coolant or poor circulation (for example a thermostat problem)
Possible — needs testing- Why it ranks here
- TroubleCodes.net lists low coolant and thermostat trouble as causes, so the cooling system itself should be ruled out.
- What would change this
- Rises if coolant is low or the engine warms unevenly. Falls if the system is full and heats normally.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: With the engine cold and off, check the coolant level and look for leaks or a broken drive belt.
IfCoolant is low or there is a leak
It meansFix the leak and refill, then see if the code returns.
Points to: Low coolant or poor circulation (for example a thermostat problem)
IfCoolant is full
It meansCheck the sensor wiring.
Step 2: Inspect the sensor connector and wiring for corrosion, burnt or brittle insulation.
IfDamage or corrosion is visible
It meansRepair the wiring or connector.
Points to: Damaged, shorted or corroded sensor wiring or connector
IfWiring looks fine
It meansTest the sensor.
Step 3: Watch coolant temperature on a scan tool as the engine warms and compare it with when the fan comes on.
Warning:A hot engine, moving fan and belts can cause burns and injury. Never open the radiator cap while hot.
IfThe reading jumps, stays fixed or does not match the real temperature
It meansThe sensor is suspect.
IfThe reading is steady and plausible
It meansTest the circuit voltage and ground at the sensor, or suspect the cooling system.
Points to: Low coolant or poor circulation (for example a thermostat problem)
Symptoms
- Check engine light
- Engine may seem normal at first
- Temperature gauge climbing or coolant warning Gets more serious: stop and have it checked.
How to fix
Step 1: With the engine cold and off, check the coolant level and look over the sensor connector for damage.
Parts and cost context
- Engine coolant temperature (ECT) sensor:Test the wiring and the sensor before replacing it. 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
JeepYour car
2025–2026 · Compass
Supported by vehicle dataJeep bulletin 08-115-26 REV. A covers a coolant temperature sensor malfunction with the MIL on and P0115-00 set on the Compass, but its summary says it is not applicable to vehicles built for the US market. Whether it is still current is not verified.
08-115-26 REV. AStatus unverified
Coolant temperature sensor malfunction, DTC P0115-00 (marked not applicable to US-built vehicles)
2025–2026compass · issued · NHTSA 11030408
Revision A of a Jeep bulletin for a coolant temperature sensor malfunction with the MIL on and DTC P0115-00 set. The summary is headed "not applicable to vehicles built for US market" and does not give the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
No curated relationships for P0115 yet.
P0115 questions
Is it safe to drive with P0115?
Briefly, if the temperature gauge stays normal. Stop if the engine starts to overheat.
Sources and review
- P0115 trouble code summary
- 08-115-26 REV. A: Coolant temperature sensor malfunction, DTC P0115-00 (marked not applicable to US-built vehicles)
- On-Board Diagnostic Trouble Codes (generic code title list)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
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