P0115
Fix within 1-2 weeksYour engine computer isn't getting a proper signal from the engine coolant temperature (ECT) sensor.
Code P0115 means your engine computer isn't getting a proper signal from the engine coolant temperature sensor. Common causes: Faulty ECT sensor (70%), wiring issues (25%), low coolant (5%). Drivability: Yes, safe to drive, but fix within 1-2 weeks. Repair cost: $50-$150 DIY, $150-$350 professional.
Can I Drive With P0115?
Yes, safe to drive
No restrictions, but fix within 1-2 weeks to prevent further issues and improve performance.
Stop driving immediately if: Flashing Check Engine Light, engine overheating, significant power loss, or unusual noises.
Symptoms of P0115
- 1Check Engine Light is on
- 2Engine running rough or stalling
- 3Poor fuel economy
- 4Engine hard to start, especially when cold
- 5Engine cooling fan running constantly
- 6Engine overheating (less common, but possible if sensor reads too low)
- 7No heat from the vehicle's heater (less common, but possible if sensor reads too high)
Common Causes of P0115
Parts most likely causing this code, ranked by probability
The sensor itself has failed and is sending an incorrect or no temperature signal to the engine computer.
70% of P0115 cases are fixed by replacing this part
Damaged wires, corroded terminals, or a loose connection in the ECT sensor circuit prevent a proper signal.
25% of P0115 cases are fixed by repairing the wiring or connector
If the ECT sensor is not fully submerged in coolant, it cannot accurately read the engine's temperature, leading to erratic or incorrect readings.
5% of P0115 cases are fixed by topping off coolant
Check These First (Before Buying Parts)
- Check your engine's coolant level and top it off if it's low.
- Visually inspect the electrical connector on the Engine Coolant Temperature sensor for any signs of corrosion, dirt, or loose connections.
How to Diagnose P0115
- 1Check the engine coolant level and top off if necessary.
- 2Visually inspect the ECT sensor connector and wiring for any signs of damage, corrosion, or loose connections.
- 3Use a multimeter to test the resistance of the ECT sensor at different temperatures (if accessible and you have specifications).
- 4Use a scan tool to monitor the ECT sensor's live data and compare it to the actual engine temperature (e.g., using an infrared thermometer on the thermostat housing).
- 5If the sensor and wiring appear good, test the continuity of the wiring from the sensor connector back to the engine control module (ECM/PCM).
P0115 on Popular Vehicles
Honda Civic
2006-2024ECT sensor failures are common on these models, often around 100,000 miles. Inspect the sensor connector for corrosion.
75% fixed by replacing the ECT sensor
Toyota Camry
2007-2024Similar to Hondas, the ECT sensor is a frequent culprit. Check for any signs of coolant leaks around the sensor housing.
70% fixed by replacing the ECT sensor
Ford F-150
2004-2024ECT sensor failures are common. Also, inspect the wiring harness leading to the sensor for chafing or damage, as this can be an issue on trucks.
65% fixed by replacing the ECT sensor, 20% by wiring repair
Frequently Asked Questions
What does P0115 mean?
P0115 indicates that the engine's computer (PCM) has detected a malfunction in the circuit for the Engine Coolant Temperature (ECT) sensor, meaning it's not receiving a reliable temperature reading.
Can I drive with P0115?
Yes, you can drive safely with P0115, but you need to fix it within 1-2 weeks. The engine computer will use a default temperature value, which can lead to poor fuel economy, rough idling, and increased emissions. Stop driving immediately if your engine starts to overheat.
Will P0115 clear itself?
No, P0115 will not clear itself. The engine computer stores this code until the underlying issue is resolved and the system passes its self-test, or until it's manually cleared with a scan tool.
How do I fix P0115 myself?
Start by checking your coolant level and inspecting the ECT sensor's wiring and connector for damage. If those are fine, the most common fix is to replace the Engine Coolant Temperature sensor itself. You'll need to drain a small amount of coolant first.
How much does it cost to fix P0115?
The cost to fix P0115 is typically $50-$150 for DIY, which covers the sensor and coolant. A professional repair at a shop will cost $150-$350, including parts and labor.
P0115 keeps coming back - why?
If P0115 keeps returning, it indicates the initial repair didn't address the root cause. This often points to a wiring issue that was overlooked, a faulty connector, or a rare problem with the engine computer itself. Ensure the new sensor is high quality and the coolant level is consistently correct.
Will P0115 fail emissions/smog test?
Yes, P0115 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure, and the underlying issue can also lead to higher emissions.
What's the difference between P0115 and P0117/P0118?
P0115 indicates a general malfunction in the ECT sensor circuit. P0117 (Circuit Low Input) means the sensor is reporting a voltage that's too low (often indicating a short or open circuit), and P0118 (Circuit High Input) means the sensor is reporting a voltage that's too high (often indicating an open circuit or bad ground). P0115 is a broader code, while P0117/P0118 are more specific about the nature of the electrical fault.
P0115 on Honda Civic?
On Honda Civics, P0115 is frequently caused by a failing Engine Coolant Temperature sensor, especially on models with higher mileage. It's a common replacement item, and checking the wiring for rodent damage is also a good idea.
Questions to Ask Your Mechanic
Did you check the live data from the ECT sensor with a scan tool and compare it to an actual temperature reading?
Good answer: Yes, the scan tool showed the ECT sensor reading -40°F, but the engine was warm, indicating a sensor or circuit issue. We also verified the coolant level.
What did you find when you inspected the ECT sensor's wiring and connector?
Good answer: We found some corrosion on the connector pins, which we cleaned, but the sensor itself was still giving erratic readings, so we replaced it.
Repair Cost Estimate
DIY Repair
Parts only
$50-$150
Shop Repair
Parts + labor
$150-$350
Save $100-$200 by doing it yourself
Difficulty
beginner
Time
0.5-1.5 hours
Beginner-friendly. Replacing the ECT sensor is typically a simple task requiring basic hand tools and minimal mechanical experience.
Cost of Waiting
Ignoring P0115 leads to poor fuel economy, rough engine operation, and increased emissions. If the engine computer receives a false low temperature reading, it will run the engine rich, which can damage your catalytic converter ($800-$2,500 repair). A $50 sensor fix now prevents a much larger bill later.
While You're In There...
You will likely drain some coolant when replacing the sensor, so it's a good time to top off or replace old coolant.
Tools You'll Need
- Socket wrench set
- Screwdriver
- Drain pan
- Multimeter (for testing)
- Pliers (for hose clamps)
P0115 is a very common sensor code. It's usually a straightforward fix, and your engine will run more efficiently and reliably once it's resolved.
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Your Next Steps
Step 1: Check your engine's coolant level and inspect the ECT sensor's electrical connector and wiring for any visible damage or corrosion.
Step 2: If the coolant level is good and the wiring looks fine, replace the Engine Coolant Temperature sensor. This is the most common fix.
Step 3: Parts you'll likely need: A new Engine Coolant Temperature sensor and fresh engine coolant.