Nissan Altima Coolant Temperature Sensor Replacement (2013-2018)
About this video
Check engine light with a coolant temperature code, gauge reading wrong, or the fans running the moment you start the car? An ASE certified mechanic shows how the engine coolant temperature sensor works, how to test it before spending a dime, and how to replace it without making a mess or trapping air in the cooling system.
SAFETY FIRST
Never open the cooling system or pull a sensor on a hot engine. Hot coolant sprays under pressure and causes serious burns. Let the engine cool completely, keep hands clear of the cooling fans, which can start on their own, disconnect the negative battery terminal before unplugging the sensor, and catch and recycle spilled coolant because it is toxic to pets and wildlife.
WHAT WE COVER
What the ECT sensor does and why the engine computer depends on it for fuel trim, idle, fan control, and timing
The difference between the sensor the computer uses and the separate gauge sender used on some vehicles
Locating the sensor on the engine and what has to move out of the way
Testing the sensor with a scan tool by comparing reported temperature to actual temperature at cold start
Checking the sensor with a multimeter for resistance as it warms up, and reading the wiring and connector for corrosion or a broken pin
Why a stuck open thermostat sets the same code as a bad sensor, and how to tell them apart before you buy anything
Draining enough coolant to keep the spill under control
Removing the old sensor, installing the new one, and torquing it without cracking the housing
Refilling and burping the cooling system so no air pocket gives you a false reading
Clearing codes and verifying the temperature reading climbs normally
SYMPTOMS YOU MAY NOTICE
Check engine light with a coolant temperature code
Temperature gauge reading cold, pegged hot, or jumping around
Cooling fans running at full speed right at startup or never coming on
Heater blowing cool air because the computer thinks the engine is already warm
Hard cold starts, rough idle when cold, or a long warm up
Poor fuel economy from the engine staying in open loop and running rich
Black smoke or a fuel smell at startup
Overheating or an engine that never reaches full operating temperature
RELATED FAULT CODES
Coolant temperature codes such as P0115 circuit malfunction, P0116 range and performance, P0117 circuit low, P0118 circuit high, P0119 intermittent, and P0125 insufficient coolant temperature for closed loop fuel control. P0128 coolant temperature below thermostat regulating temperature shows up constantly here and is usually a thermostat, not the sensor, which is exactly why the testing in this video matters. You may also see cooling fan control codes and rich or lean fuel trim codes P0171 and P0172 that clear up once the sensor reads correctly.
DOES THIS APPLY TO MY CAR
Recorded on a 2018 Nissan Altima, fifth generation L33, sold 2013-2018 in the US with the facelift covering 2016-2018. It applies to 2013 2014 2015 2016 2017 2018 Altima models with the 2.5L QR25DE four cylinder and the 3.5L VQ35DE V6. The QR25DE is also found in the Nissan Rogue, Sentra, X-Trail, and Frontier, and the VQ35DE is found in the Nissan Maxima, Murano, Pathfinder, Quest, 350Z, and Infiniti G35, M35, and FX35, so the sensor location and the test procedure carry over to those vehicles. The Altima is sold as the Nissan Teana in many markets. Every modern engine uses a coolant temperature sensor the same way, so the diagnosis applies to Toyota, Honda, Ford, Chevy, Hyundai, Kia, Subaru, Volkswagen, BMW, and Mercedes-Benz.
Popular searches this video answers: coolant temperature sensor replacement, bad coolant temp sensor symptoms, P0128 code, P0117 code, P0118 code, how to test a coolant temperature sensor, temperature gauge not working, cooling fans running all the time, no heat from heater, Nissan Altima coolant temp sensor.
DISCLAIMER: This video and description are provided for educational purposes only. Vehicle repair carries risk of injury and property damage. You are responsible for your own safety and for any work performed on your vehicle.
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